Citation Analysis as a Tool in Journal Evaluation Journals can be ranked by frequency and impact of citations for science policy studies. Eugene Garfield [NOTE: Tbe article reptintedbere was referenced in the eoay vbi.b begins m @g. 409 is Volume I, IIS ia. #dverte#t omission W6Sdiscovered too Me to iwctnde it at it~ proper Iocatioa, immediately follom”ag tbe essay )
As a communications system, the net- quinquennially, but the data base from work of journals that play a paramount which the volumes are compiled is role in the exchange of scientific and maintained on magnetic tape and is up- technical information is little under- dated weekly. At the end of 1971, this stood. Periodically since 1927, when data base contained more than 27 mi[- Gross and Gross published their study tion references to about 10 million dif- (1) of references in 1 year’s issues of ferent published items. These references the Journal of the American Chemical appeared over the past decade in the Socie/y, pieces of the network have footnotes and bibliographies of more been illuminated by the work of Brad- than 2 million journal articles, commu- ford (2), Allen (3), Gross and nications, letters, and so on. The data Woodford (4), Hooker (5), Henkle base is, thus, not only multidisciplinary, (6), Fussier (7), Brown (8), and it covers a substantial period of time others (9). Nevertheless, there is still no and, being in machine-readable form, is map of the journal network as a whok. amenable to extensive manipulation by To date, studies of the network and of computer. the interrelation of its components have In 1971, the Institute for Scientfic been limited in the number of journak, Information (1S1) decided to undertake the areas of scientific study, and the pe- a systematic analysis of journal citation riods of time their authors were able to patterns across the whole of science consider, Such shortcomings have not and technology. It began by extracting been due to any lack of purpose, in- from the data base all references pob- sight, or energy on the part of investi- Iished during the last quarter of 1969 gators, but to the practical difficulty of in the 2200 journals then covered by the compiling and manipulating manually SCL The resultant sample was about 1 the enormous amount of necessary data. million citations of journals, books, re-
A solution to this problem of data ports, theses, and so forth. To test is available in the data base used to whether this 3-month sample was rep- produce the Science Citation Index resentative of the year as a whole, it ( SCI ) (10). The coverage of the SCI was matched against another sample is international and multidisciplinary; it made by selecting every 27th reference has grown from 600 journals in 1964 from the approximately 4 million ref- to 2400 journals in 1972, and now in- erences collected over the entire year. cludes the world’s most important sci- The two samples were similar enough entific and technical journals in mow in scope (number of diflerent items disciplines. The SCI is published quar- cited) and detail (relative frequency terly and is cumulated annually and of their citation by different journals) to
527 ITEM CITEO JOURNA1 TOTAL NUMBER OF T! ME SC ITED NO 1569 19SS 1%7 19S$ 1%5 1%4 1%3 1S82 1%1 19s9 REST
00243 ACTA PATII JAP 36 1 334673 36 @3244 ACIA PATH MICROBIOL 736 29 69a7595s 59444am 31 234 00909 AM J ANAT 637 7 27 37 5S32411526~5 21 3s0 Ooalo AM J BOT 1171 13 74 B7 6S 73 as 57 57 47 49 6s0 00911 AM J CANCER 103 103 00S12 AM J CAROIOL 123a 73 XM 1SS 247 134 70 78 66 53 73 44 03591 cAN J SOIL SCl 33 21412663 26 03592 cAN J SURG 61 2 6431311335 1 10 03593 CAN J TECH 3 .,. 3 035s4 cAN J ZOOL 356 46 3a40m24m192a17 22 73 06990 ISRAEL J AGR RES 29 1 1718721 .1 Oaaal ISRAEL J BOT 16 35431, 06992 ISRAEL J CHEM 91 14 251a lol167. ~~ 0%51 J INVEST OERM 6S5 24 ra al 696546303134 22 215 0S652 J IOWA MED SIX 13 5..125 09653 J IRISH MED ASS 16 1 3433. . .2 133s0 PCALIF ACAD SCl 18 143.1. .9 13391 P CAMBRIDGE PHIL SOC ma B 22 23 11 12 9 13 11 17 3 260 19755 ZANGEWCHEM 47 1’11 143 1975S Z ANGEW ENT 35 1142411 5 16 19757 Z ANGEW GEOL 49 2 75a5544 216 1975s Z ANGEw MATH 10 1 1 1111.4 Fig. 1. Juurnai citation frequencies. The data show the total number of times each journal was cited during the last quarter of 1969 and the distribution by publication date of the particular issues cited. The journals shown were taken from a list of more than 20,000 items (journals, books, reports, theses, and so on) cited during the last quarter of 1969 in journals covered by the SCI. convince us that the 3-month data con- and the distribution by year of publi- stitute a valid sample. cation of cited items. A portion of this With this data from the last quarter listing is shown in Fig. 2. of 1969, ISI produced three listings that The third listing is similar to the sec- should greatly further efforts to map ond, but it arranges the data by citing the network of journal information journal rather than by cited title. The transfer. The first listing is accumulation listing shows, for each journal covered of all citations of the same titles. It by the SC1, the number of references gives the number of times each different published in issues processed for the title was cited during the last quarter SCI during the last quarter of 1969, of 1969 and distributes that total over and it breaks that total down by publi- the years in which cited issues, editions, cation date of the items to which refer- and so on were published. This distri- ence was made. The listing further iden- butionis shown byyear from 1969 back tifies all titles cited in those references to 1960 and in aggregate form for ear- and the frequency with which @heyare lier years (l I). Sample items from this cited. As in Fig. 2, the counts for each listing are shown in Fig. 1. cited title are broken down by year of The second listing is a detailed cita- publication. A portion of this listing is tion history of each cited title. It shows shown in Fig. 3. how frequently each title was cited and, These listings afford, I believe, a new as above, gives subtotals by year of view of the literature in scientific and publication, These citation totals and technical journals. Before discussing sutstotals are further broken down to some of its implications, however, I show how frequently each journal cov- note possible limitations of the data ered by SCI cited the title in question and problems encountered in analyzing
528 CITED JOURNAL NuMBER OF TIMES CITED CITING JSINL TDTAL 1S69 1968 1967 1966 1S65 1964 1963 1S62 1S61 19S0 REST J LINN SOC BOT ======>j~. ..= Q=.. 3=.. 0=== 3=== 1 === o=== o=== o=== 1 === 1 === 8 NEW PHYTOL 50101000 0102 ALL OTHER (10} .------12 ------0------2------0 ----.-2------1------0 ------0------0-----0 ------1---.--6
J LIPID RES ======> 902” ==33= 106= 109== 96= 133= 121 == 75== 63== 60== 56==24 BIOC BIOP A 635816613154 6514 BIOC HEM J ------39 ------0--. ---4 -----.7 ------3.----- 6--..--7 ------3------3----.-4 ------1------1 J BIOL CHEM 390673636 2220 J CHROMAT ------30 ..-.-.2---. --3---.--4 ------4------2------6 ------0----,4 ------2 ------1..--.-2 JCLIN INV 291333722 3311 J LIPID RES ------28 -..-..5 -.--.-5-.-... 4------2----.4 ------1.-.--- 2------0----- 3----- 1------1 P SOC EXP M 25031343 25112 MI LIT MED ------5 ------0-.---- 0...-..2 -.-...0 ------0.-.-.. 0----. 1------1------0----. 1------0 NY ST J MED 50112000 1000 ALL OTHER (123) ----.----.---.219 ...... 6--.19 --.-16 ----29 .--- 43--27---.23---- 15----- 15---- 23-----3
J LONO MATH SOC =====> 173’ == 16== 19== 19== 11 ===8== 10=== 2=== 8=== 4=== 8==68 J LOND MATH 71 8 12754404 2421 TAM MATH S ...... 11 ...-..2 -..1.-----2-- .--1 --.--- 0.---..0 ------0-.-. --1 .---.- 0------0 ------4 P CAMB PHIL 8 1030000 0004
Fig. 2. Statistics on cited journals. The data on cited journals show the total number of times each journal was cited in the last quarter of 1969 and the distribution by publication date of cited issues. For each cited journal, the figure identifies all other journals (“citing journals”) that referred to it five times or more during the quarter year (and the distribution of these citations by publication date of cited issues). Journals that referred 10 the cited journal less than five times are grouped as “all other. ” The data were taken from a complete list of journals cited during the last quarter of 1969 in journals c{wered hy the SC1. the sample. journals’ rankings. Such may be the The SCI data base is, to my knowl- case, for example, with certain journals edge, the largest and most extensive of in foreigtt languages, particularly those its kind. It does not. however, cover that do not use the Roman alphabet. As every scientific and technical journal. is true of most secondary services, the (Nor, as seems likely in view of find- SCI is less likely to cover a journal that ings discussed later in this article, need presents problems of transliteration (or it attempt to. ) The list of most fre- transcription) and translation than one quently cited journals (the first 152 of that does not. It may !be, therefore, that these journals are given in Fig. 4) shows this fact has adversely influenced the that the SCI has been remarkably suc- ranking of Russian and Japanese jour- cessful in covering all “significant” and nals, for example, which probably cite “important” journals, insofar as citation other Russian and Japanese journals counts can be considered a reliable mea- more frequently than do journals in sure of “importance” and “significance.” other languages. Whether such an un- It is, of course, possible that one or derrepresentation exists, and, if so, to more journals not covered by the SCI, what extent, is difficult to determine. and thus not represented in the data Nevertheless, Soviet information scien- here, may cite themselves and other tists have reported that the SCI does a journals so frequently that their inclu- surprisingly good job of covering Soviet sion would alter their own and other journals. In fact, Soviet scientists seem
529 to have made more use of citation anal- more wtdely and more frequently than ysis in studies of science policy than it actually does on the average. Or. a have any other scientists ( 12–14 ). journal may have published an article One must remember that the listings that has since been cited with extraordi- were prepared from a 3-month sample nary frequency (/5). In such a case, a of journal issues. The size of the sample single article will have had an inordi- is certainly more than adequate for sta- nate influence on the r~nking of the tistical purposes, and, as noted, the )ournal ( 16). Finally, a journal that sample has been matched against an- publishes relatively few articles, but other sample of more than adequate articles of high quality that both cite size. It is nevertheless possible that ran- and arc cited frequently, may seem to dom events in journal publishing have have considerably less impact than it introduced some degree of distortion, actually does, particularly if the journal For example, a journal may hirvc, in appears infrequently or irregularly and ~+c time period covcrcd by the sample, thus cscapcs representative inclusion in departed from its usual policy of ac- a sample of this type. cepting only original research commu- In antilysis of the sample, an im- nications and published one or two mensely irksome problem was the in- review articles wltb extensive hibliog. consistency with which different authors raphics. In the sample, that journal and editors abbreviate journal titles in would appear to cite other publications their rcfcrcnces. As far as possible, this
SOURCE JOURNAL NUMBER OF TIM ES CITEO REFERENCE JOURNAL TOTAL 1969 1968 1967 19s43 1965 1964 1963 1962 1961 1960 REST J LIBR AUT ‘======> 168* ‘= 15== 50== 35== 19=== 8== 14=== 5=== 6=== 3=== 1 == 12 PROGRAM 15 36510000 000 J LIBRARY AUTOMAT ION---- 7 -...-.3. -.4.. ..-.0 ------0.- ....0-. ---0..---0 -.-..0----..0 --.0 ------O ALL OTHER (120) 146 9 40 30 18 814563112
J LIPIO RES ‘======> 313* ‘= 15== 36== 35== 26== 25== 29== 20== 10== 15== 15==87 J BIOL CtiEM 43 26361310 1119 J LIPID RES -.-...-..-....-.---..-..2S .-..-- 5... -.5--...-4 ...-.-2.. -...4 ------1 ...-..2 ...... 0------3.----. 1....-1 BIOCHtM BIOPHYS ACTA 19 13132310 221 BIOCHEM J ...... 13 ....-- 1 -..--. 1..-..- 3..-. --0 ...... 0------0-..--. 1 ..-...2 ------1 ..-... 1-----.3 J AMER CHEM SOC 12 00000000 loll BIOCHEMISTRY ...... - 9 .--.-.0. -----3..-... 0.-.. -.2-.--.. 1.-...-2 -..-..1 -.-...0 .-..-. 0... ---0 .--.--0 J CHEM SOC LONDON 5 00100000 103 J CHROMATOGR ...... 5 .--...0 -...-.1..-... 1 .--.-.1 -.-..-0..-..- 1 -...-.0.. -... 1.-.---0 -.....0. -..--0 METHODS ENZYMOL 5 00000001 004 ALL OTHER (89}------124 -..--.5 .... 12 ....19---- 10...-..8.-..16-.--10 -.-...2 --.--.5 ..-...6 ...-31
J LOND MATH ======> 743” == 21 == 44== 58== 52== 42== 34== 31 == 38== 29== 33= 361 J LOND MATH 52 6 12554302 1311 P LONDON MATH SOC -.. 37 -...... 4.- ....5.-.-..7 .-...- 1 --..-.2 ...... 2 .-... -0.. --..1 --..--1 ...-..0 .-..14 Fig. 3. Statistics on citing journals. The data on each citing journal (“source journal”) show the total number of references each journal contained in the last quarter of 1969 and the distribution of [hat total by publication date of journal issues referred to. For each citing journal, the figure identifies all journals (“reference journal”’) cited five times or more during the quarter year (and gives the distribution by pub- lication data of cited issue). Journals cited less than five times are grouped as “all other.” The data are taken from a list of journals processed for the SCl during the last quarter of t 969.
530 inconsistency has been ]i?ininlized by side a regularly enumerated series must standardizing all variants of the same be accounted for. In a few cases, jour- titles and their abbreviations. Some idea nals periodically change their titles on of the work involved in this standardiza- single issues to note special subject mat- tion can be had from the fact that there ter (18). Serials librarianship abounds were more than 100,000 different ab- in difficulties of this type, and there is breviations for the 12,000 individual frequently disagreement on how best to journal titles cited in the ~-month sam- handle them. Briefly: a journal pub- ple ( /7). Inconsistency was made worse lished in sections is considered a single by inaccuracy. In some cases, it was journal: translations of journals are possible 10 disentangle the results of identified with the original versions; bibliographic carelessness—as, for ex- changes of title have been ignored and ample, when Sol. St. Phys. proved to previous volumes attributed to the cur- have been used indiscriminately to rent title; journals absorbed or incorpo- ident ify Solid State Physics (Academic rated by other journals have been cred- Press ): Solid Stute Physics, Proceedings ited to a new or remaining title; supple- o~ the Ph.vsica] Socie!v, London; So vict ments have been considered as issues in Phy.sic,r Solid Stare ( a cover-to-cover the regular series. For the purposes of translation of FiZika Tverdogo Tela ); this analysis, such arbitrary decisions and even Physira Stutus Solidi ( Akade- seem justified; as required in the future, mic-Verlag). In other cases, however, it the raw citation data can, of course, be was impossible, without going to in- compiled and manipulated in such a ordinate expense, to determine exactly way as to differentiate between changed which journal was being cited—for ex- titles, sect ions, translations, and so ample, when Arm. Phys. was found to forth. have been used for Annalers der Physik, Annuls of Physics, and Annales de Physique. Itis not surprising that the Some Preliminary Analyses editors of at least one publishing house, having decided that the problem of Figure 4 shows the result of a fa- unique and unambiguous journal title miliar application of citation analysis. abbreviations is simply insoluble, now It is a listing of journal titlq ranked by use full titles in every reference to a the frequency with which they were journal. cited in the references of journals in- Finally, it was necessary to make dexed for SCL This partial listing gives some arhi trary decisions in order to the top 152 of the 565 most frequently avoid unduly complex bibliographical cited journals of science and technol- technicalities. Journals merge; they split ogy. (The top 152 accourrt for 50 per- into new journals, or into “sections” cent of all references to journals. ) that may be pubIished separately or to- It is apparent, even from the makeup gether. They change titles, with or with- of this partial listing, that a good multi- out continuing their numbering of vol- disciplinary journal collection need umes and issues. Some journals appear contain no more than a few hundred in one or more translations; some such titles. That is not to say that larger col- translations are complete, others selec- lections cannot be justified, but it does tive, and some are similarly, others say something indisputable, in terms of differently, numbered. Supplements out- cost and benefit, about how large rsjour-
531 1Wm No. (11 (2) [31 (4)
1 J AM CBEM SOC 2b323 22156 3946 blb 2 PHYS REV 206?4 20740 5767 596 J BIOL CHEM 17112 10768 1777 059 : NATuRE LONDON 15325 15956 68L1 342 J CHEM SOC 14028 177b4 5827 048 : J CHEM PHYS 13690 11696 3738 128 SCIENCE 9752 11880 ;:;? 993 i B1OCHIM 810PHv S;U; :TA 9550 10956 102 P NAT ACAD SC I 8260 11548 1348 Sbb 1; W;; M J 7638 b34f3 2074 060 11 7617 8164 5496 485 12 PHYS REv LETT b581 11380 2317 ‘?11 13 CR ACAO SC I 578q 6576 8345 780 AM J PHYSIOL 5420 3156 1013 115 ;: J ORG CHEM 5401 5756 2475 325 lb J APPL .. ‘-”<”!. 5190 5072 2800 161 P SOc ExP BIOL MEO 5079 3468 1;;; 806 :: J MOL i310L 4982 7340 .911 19 J PHVSIOL LONO 4966 3036 1248 432 20 P ROY SOC LONO 4064 1916 621 085 J CELL EIOL 4813 4596 1357 386 :; J CLIN INVEST 4785 3652 1086 362 23 J PHVS CHEM 4703 4516 1’?3’9 329 24 CHEM BER 4541 2120 1037 052 25 NEW ENGL J MEO 4512 5252 ;:;: 359 2b J AM MEfJ ASS 4492 3980 :;; 27 BRIT MEO J 4304 4224 6;;: 28 SOV PHYS JETP 4295 3400 509 29 AS TROPHYS J 4271 5440 11b7 661 30 ANALYT CHEM 4259 2424 1510 605 31 J BACTERIOL 4147 4712 1410 341 32 BIOCHEMISTRY 4076 6344 1114 b9d 33 N!JCL PHVS 4034 6716 2345 ;;: 34 PH”~!,, ..!!,=~. 3943 7160 30>4 35 ,. TRAHEORON LETT 3’937 0252 2902 ;;; 3b J’Ex P MEO 3871 2700 325 37 ANN NY ACAO SC I 3787 2344 1216 927 38 ARCH BIOCHEM BIOPHYS 36/39 3776 1169 230 J GE OPHYS RES 3537 5312 15b9 385 :: t .0(. . . .“...... 345a 2888 2069 395 41 il’OCHEM 810 PHYS RES 3417 5108 11’20 292 42 FED P 3372 4036 7374 547 43 J PHYS 3300 3256 2379 368 T FARADAY SOC 2922 1808 879 056 :; ACTA CR YSTALLOGR 2917 216.4 1803 200 46 DOKL AKAO NAUK SSSR 2069 245b 5385 456 47 J PHARMACOL ExP THER 2781 2020 5bb 568 48 ~Nf~u::fM 2728 3660 1251 925 49 2b27 2’992 72b 121 50 INORG .,1‘U .!.!CIfi 2620 3976 1247 188 51 Sov PtHYS[:~L]D STATE ;:6.: 2984 1561 911 52 CIRCULATI 2b24 2160 214 53 ENOOCR INOILOGV 254B 2276 783 90b 54 ~:::o CHEMA SC AND 2444 1984 943 103 55 CIMENTO 2431 3436 1’ 938 772 CHIM FRANCE 2416 2664 2704 9B5 56 B Soc . . 57 vIROLIJb Y 2376 2620 584 486 58 CANCER RES 23.49 2344 814 879 CAN J CHEM 2280 2392 1182 023 :: HE, . ” C“l M APTA 22a9 1524 539 827 61 z NATti R60Riz Hij NG ;:$: 2172 1650 316 AMA J MEO 1784 395 516 :: J .~AB ~~!N MEO 2120 1284 754 702 64 TETRAHEDRON 2071 3220 1313 452 65 EXP CELL RE s ;:;; 1464 653 241 66 LIE EIGS ANN 1 CHEM 768 492 5bo 67 ANN [1NT MEO 1946 1044 1098 b79 6.9 PHIL MAGI 1943 1L80 547 157 69 J CLI! N EW:5LMETAB 1903 1888 488 868 70 J APPL PH 1836 1460 643 270 71 ACr..,- ..0“” Fig. 4. The 152 most frequently cited journals ranked by frequency of cilalion in journals covered by Ihe SCI. Column 1 gives rank, and column 2 gives abbreviations of the titles of cited journals. Column 3 shows the total number of limes each journal was cited during the last quatier of 19s39. Column 4 gives an estimate of the total number of citations in 1969 of items published in 1967 and 532 1ass Cnationsto 4r3k3m Item Clke *UT alla 1s68 ?UA3k3WdIn No. hwrnti Artkk% 1U7 and 196a (1) (2) {4] (s) 77 AM J OBI: T,: WO:YNECOL 657 1440 11’73 1 207 ;: PLAVT PHY b4b 1808 1149 1 573 IND ENG ClHEM b44 ‘?28 856 1 084 80 ANN SURG 641 1036 642 L b13 81 B CHEM SO’IC JbP 639 2004 1::; 1 27B 82 EuR J BIO ICHEM b35 L992 3 97b 83 GENETICS 618 1340 738 1 815 BLOOD 614 1256 5b6 2 219 :: P IEEE 610 1856 756 2 455 86 J OPT SOC 587 1196 1322 0 ‘?04 87 $N:; ;7 ..RI( O:!EM 519 1672 502 3 330 88 PHYslo L 507 1208 407 2 968 89 ARCH IINTERN MED 501 860 486 1 7b9 90 AM HEART J 453 1036 539 1 922 J ExP PSVCHOL 449 1152 644 1 788 :; J GEN MI CR OBIOL 445 1136 534 2 127 v> J COMP PHYSIOL PSYCH 444 888 47b 1 8b5 J PHYS CHEM 50 LIOS 430 1572 801 1 9b2 :: CANCER 416 1224 593 2 0b4 ?b AM J P-,.,’_’,--1. !JL 401 ‘?60 529 1 814 97 J PHYS (HEM 400 lllb 1545 0 722 98 IS ENZYMOL 391 145b 482 3 020 RG NUCL CHEM 391 1356 908 1 493 l:; TRICS 382 1::: 709 1 495 101 3YNECOL OBSTET 374 535 1 622 102 ?EC 365 752 183b 0 409 103 >0 Pnvs 364 81b 18. 4 3]7 104 SOC AIME 35’? 11’36 901 1 327 .“. . 105 ., l,.? 352 215b 101’J 2 115 106 J PHARMACO1 348 1348 507 2 b58 107 337 2556 72; 3 545 108 32’? 2192 148> 1 476 109 308 1::: 1538 0 7e5 110 304 452 2 132 111 304 1548 1050 1 474 112 297 1592 15b5 1 017 113 286 1428 1244 1 147 114 286 1800 653 2 756 115 274 996 7’?0 1 260 116 .-. ., ,,..,,. 273 ‘?68 1]48 0 043 117 I J I?OENTGENOL 272 1044 Bbo 1 213 118 ii fiA J 269 1.45b L231 1 182 119 1 ASME 246 000 1332 0 600 120 I J CA ROIOL 238 1600 737 ; ;:; 121 JI HIS TO CHEM CYTOCHEM 229 020 362 122 J PEo [AT 229 1076 783 1 374 123 J ACOUST SOC AM 21q 1016 :j:; 0 4b2 lza ~A; :W~ISSENSCHAF TEN 218 ‘?44 O 8b5 125 209 952 489 1 946 12b SPECTROC141M ACTA 201 1248 67Q 1 837 127 Z ANORG ALLG CHEM 108 580 54+ 1 Osb 128 J PERSON SOC PSVCMOL 106 b7b 581 1 163 129 RAOIOLOGV 175 1244 635 1 489 130 :Ml .I -.afll 171 644 726 : ;:; 1>1 ~HYS CHEM LEIPZIG 170 332 252 132 J LMRU‘3 MA TOGR lbl 1708 1343 I 271 133 HOPPE SE YLERS z 145 1412 8b3 1 b3b 134 J UROL 142 656 712 0 92L 135 ARCH PA THOL 138 556 60’9 1 359 13b ARCH SURG 134 748 867 0 862 137 AM J 01S CH ILO 127 748 610 1 22b 138 ACT4 MEO 5cAN0 112 6.80 472 1 440 139 ANN PHYSICS 105 b92 224 3 089 140 COLD SPR HARB SYMP 091 Lobo 194 ; ::; 141 J ORGANOME1 CHEM 089 2784 ?96 142 pFLu GEC’C. . . .,.Pw. . .. 083 896 732 1 224 143 (lPT <0-PECTROSC uSSR 076 1100 814 1 351 144 ~LIN wSCHR 057 800 1198 0 667 145 CHEM INO LONO 049 648 1703 0 380 146 BER SUNSEN PHYS CHEM 044 608 771 0 692 147 BIOCHEM PHARMACOL 030 1292 684 1 888 148 PHYSIOL REv 022 572 17 333 149 J BONE JOINT SURG 021 500 1:; 0 b71 150 J F6EuROPHVS[OL 015 6’?2 156 4 435 151 CR SOC BIOL 010 596 1316 0 452 152 REC TRAV CUIM 010 ?28 337 2 160 1968 (the estimate was ma& by quadrupling the 1969 citations of 1967 and 1968 items in the 3-month sample). Column S shows the total number of items processed from each journal by the S(H during 1967 and 1968. Column 6 indicates the impact f=tor (average citations per published itern) derived by dividing the num hers in column 4- hy those in column 5. 533 na[ collection need be (or how small it abstracting for “total coverage” of the can be) if it is to provide effective literature ) is itself as unrealistic as in- coverage of the literature most used by formation scientists have for some time research scientists. suspected it must be (20). Meaningful It is also immediately apparent that discussion of this point—the best of the majority of all references cite rela- current serials catalogs notwithstanding tively few journals. Figure 5, which —is probably impossible in the absence plots the distribution of citations among of agreement on what, quantitatively as cited journals, shows that only 25 jour- well as qualitatively, constitutes a “sci- nals ( little more than 1 percent of SCI entific journal.” At the very least, it coverage ) are cited in 24 percent of all may be advisable to distinguish as references; that only 152 journals (those journals only those periodicals that pub- listed in Fig. 4) are cited in 50 per- lish, for example, 20 or more articles cent of all references; that only 767 a year. journals are cited in 75 percent of all The predominance of a small group references; and that only 2000 or so of journals in the citation network has journals are cited in 85 percent of all been confirmed by a weekly scanning references. In addition, the data from of SCI input to a system for selective which Fig. 5 was plotted show that only dissemination of information (SDI) 540 journals are cited 1000 or more (21). In this SDI system, a newly pub- times a year, and that only 968 journals lished article can be retrieved on the are cited even 400 times a year. When basis of journals cited in the article’s one considers that only 165 or so jour- bibliography or footnotes. This retrieval nals publish 400 or more papers a year, criterion is known in an SDI profife as the impact of the average paper must a “cited-journal question. ” A retrieval be recognized as relatively slight. In profile consisting of only 25 different fact, the average paper is cited only cited-journal questions will retrieve 50 1.7 times a year (19). percent of all articles processed for the This analysis gives good reason for SCI every week. In other words, half of concern about any increase in the numb- all articles published cite at least one er of scientific and technical journals. of the 25 most frequently cited journals It is not merely that increased numbers at least once. of journals make coverage of the lit- It is also interesting that a small erature more difficult, but that so many group of journals is found ,0 be pre- journals now being published seem co dominant when the literature is ana- play only a marginal role, if any, in the lyzed in other ways. Figure 6, for ex- effective transfer of scientific informa- ample, plots numbers of articles ptsb- tion, If one accepts the contention (high- lished against numbers of jouraals. It ly debatable, in my opinion) that there shows that, of the 2200 journals cov- are between 50,000 and 100,000 scien- ered by the SCI in 1969, about 500 tific and technical “journals,” the data published about 70 percent of all ar- presented here indicate that only 5 to ticles published. As shown in Fig. 7, a 6 percent of them are being cited, If small group of 250 journals provided such percentages seem unrealistically almost half of the 3.85 million refer- low, it may be because the estimate of ences processed for the SCI in 1969. 50,000 to 100,000 scientific and tech- The predominance of cores of journals nical journals (requiring indexing and is ubiquitous. An analysis of whti 534 Cited journals (No.) Fig. 5. Distribution of citations among cited journals. The curve shows that a rela- tively small core of 152 journals accounts for about hatf of afl citations and that only- 2000 or so journals account for about 84 percent of all citations. journals firstpublished reports of new- ford’s bibliographical law concerning ly synthesized compounds indexed for the concentration and dispersion of the Current Abstracts oj Chemistry and literature of individual disciplines and fndex Chemicus gives a similar result: specialties (2). Going beyond Brad- of the 183 journals indexed by this ford’s studies, 1 can say that a com- publication in 1969, 11 percent of the bination of the literature of individual journals accounted for 60 percent of disciplines and specialties produces a the new compounds, 22 percent of the multidisciplinary core for all of science journals for 79 percent of the com- comprising no more than 1000 journals. pounds, 32 percent of the journals for The essential multidisciplinary core 89 percent of the compounds, and so could, indeed, be made up of as few on (22). Chemical Absrracts presents as 500 journals if, for example. one is an even more striking example of th~ attempting to satisfy the needs of li- predominance: about 8 percent of the braries in developing countries. journals it covers publish more than 75 percent of the items it abstracts (23). The data reported here demonstrate Other Considerations the predominance of a small group of journals in the citation network. Indeed, Citation frequency reflects a joLlrnal’s the evidence seems so conclusive that I value and the use made of it, but there [ can with confidence generalize Brad- I are undoubtedly highly useful journals 535 Source journals indexed in 1969 (No.) Fig. 6. Distribution of the number of published items among the ar?proximalely 2200 joumafs covered by the SCI in 1969. The curve shows that a relatively small core of journals carried the majority of items published. that are not cited frequently. Scientists function of many variables besides sci- read some journals for the same reason entific merit. Some of them are known people read newspapers—to keep up or can reasonably ‘be assumed: an au- with what’s going on generally—and thor’s reputation, controversiality of they may rarely or never cite such subject matter, circulation, availability journals in their published work (24). and extent of library holdings, reprint A popular review journal such as Scle?r- dissemination, coverage by secondary /ific American or a news-oriented jour- services, priority in allocation of re- nal such as New’ Scientisf may rank rel- search funds, and others. It is extremely atively low on a times-cited list (in difficult, even when possible, to clarify fact, Scierrfi/ic American is 449th, while the relations among such variables and New Scien/i.s/ ranks well below 1000), their relative impact on citation fre- but that does not mean that they are quency, One such variable is, however, therefore less important or less widely fairly obvious. If every article has an used than journals that are cited more equal likelihood of being cited, it should frequently. It merely means that they follow that the more articles a journal are written and read primarily for some publishes, the more frequently the jour- purpose other than the communication nal will be cited. For the most part, of original research findings. the data show that such is indeed the Citation frequency is, of course, a case. Although many articles are never 536 cited (25, 26), 1 have very rarely found time. The journal impact factor will among the 1000 most frequently cited thus reflect an average citation rate journals one that is not also among per published article (27). However, the 1000 journals that are most pro- the development of impact factors that ductive in terms of articles published. fairly relate the size of a journal during Citation frequency of a journal is {he cited years to its current citation thus a function not only of the scien- rate is a formidable challenge to sta- tific significance of the material it pub- tistical analysis. With the SC1 data base, lishes (3s reflected by citation), but it is easy to determine how frequently also of the amount of material it pub- a journal has been cited within a given lishes. period of time, but it is much more In view of the relation between size difficult to agree on a total-items-pub- and citation frequency, it would seem lished base to which such citation desirable to discount the effect of size counts can properly ‘be related because when using citation data to assess a the items may have been published at journal’s impotiance. We have attempt- any point in the journal’s history. in ed to do this by calculating a relative selecting an items-published base (28) impact factor—that is, by dividing the for each journal, I have been guided by number of times a journal has been the chronological distribution of cited cited by the number of articles it has items in each annual edition of the published during some specific period of SCI (19, p. 15; 29). An analysis of Source journals indexed in 1969 (No.) Fig. 7. Distribution of references among journals covered by the SCI in 1969. The curve shows that fewer than 300 journals provided more than half of the references processed. 537 1969 Tbm.s Clt*d cn*tlOns to Articles ● Item Cit.a Last Quarter 19S? nd 1S69 Publishedin lmDacl No. Journal 196S Artlcl.s 1 S67 :;ld 1$68 Factor (1) (2) (3) (4] (6) ?OTEIN CHEM 373 184 23 000 : 4COL REv 725 448 22 400 3 ?IOL REV 64b 804 20 615 4 ?Ev BIOCHEM 4b8 ’932 ;7 584 5 1022 572 ;7 333 b s 247 820 17 083 * 384 228 lb 285 : 291 )92 9 600 230 144 Q 000 1: 4’?82 7340 8 811 11 RES 417 232 8 5’?2 12 SA ;;;: 11548 E 56b 1> 2700 0 307 14 488 452 E 2;8 15 !,r.1 x., 1003 408 8 lbo 16 INU REv PL PHYSIOL 3 ;.! 296 7 047 17 ST GROWTH 232 820 b 5b0 18 ~E;H~~CROBIOL 254 288 b 545 17112 ;07 .58 b 059 ;: 0s BIOCHEM ANA. 285 80 5 714 21 FM IS TRY 407b b344 5 b~4 22 ?HEM Soc 26323 22:5b ..<. . IICD. . 58b 612 :; SPR HAQ8 5YMP lo~l :060 25 358 >7b 2b 560 ;8b0 27 410 240 28 552 b30 z~ 6581 11380 30 4271 5440 31 2191 1784 32 4295 3400 >3 237b 2b20 34 10)5 6’92 35 5Q3 3b8 36 l>ba 81b 37 RES >4;7 5108 38 t 50C 8b8 1008 39 175C 1020 40 2627 2992 41 437 284 42 Ibba :b72 43 1.535 ;q’az 44 30’2 564 45 .35 552 4b .,A13 1’?0) .088 47 268 392 48 ‘?29 876 49 3!8 28. 50 6>0 5b4 51 80: 1206 52 .,, . . . 2ob7A 20740 J PHARMACOL E.. THER 278: 2C20 53 . . 54 PHVS LETT 1>37 2556 55 ;ANOME1 CUE?+ )00’? 2?84 5b 8b0 b28 57 420 11.0 50 42b .!32 4813 45~b :: 3537 5312 bl 4785 1652 b2 4147 ,712 63 1;;; ;672 b4 ...... 404 65 BIOCHEM B1OPHYS 3b8q 3776 66 ; CHEM 2620 19,6 b7 !M PHYS ,>DQO l,b~o 68 J“, TRA5:RgCT RES $?7Q I>Q2 bQ 4M J PHV>[OL 5A20 )15C 70 TRAP4SPLA?U. AVOV 513 lJCO 7; B1OCMIM B: OPH*S 9550 13q5b 12 I,!4N P.. f’ig. 8. The 152 most frequently cited journals ranked by impact factor (average number of citations per item publish~d). The column hwdings are explained in the legend uf Fig. 4, 538 1s69 Cnation,to 1t,ln c nod ●67 ●nd 19s8 No. J0u,m81 Articl*l (1] (2) (4 I SCIENCE 9752 11880 39b8 2 993 ;; GE NET RES 371 464 155 2 993 J GEN PHYSIOL 1507 1200 407 2 968 :; ANGEw CHEM 2728 3660 1251 2 925 81 ENDOCRINOLOGY 2548 227b 783 2 906 82 CANCER RES 2349 2344 014 Z 879 83 ExP PA RASITOL 437 492 171 2 077 84 NUL. 4034 6716 2345 2 863 85 TETRAl+i060N LETT 3937 8252 2902 2 843 86 Pi ANTA 707 1172 414 2 830 87 HE LV CHIM AC IA 2249 1524 ;;; 2 827 88 COMP NEu ROL q69 376 2 0z7 89 OPOLYMERS 452 656 235 2 791 Qo ROMOSOMA 458 440 L59 2 767 91 ZELLF MIKR ANAT 1::: 1800 653 2 756 92 IN SC I 552 205 2 692 I T J PHARMACOL 1348 93 ----- . . 1340 507 2 658 94 399 844 321 2 629 405 332 128 2 593 :2 508 892 348 z 563 97 Soc 702 292 114 2 561 98 .-. 80! 90@ 357 2 521 99 ~A; ~~~:”PHYS 742 1508 b30 2 520 00 274 532 213 2 497 01 J( CATAL 431 764 308 2 480 02 AC11A PHYSIOL SC A?AD 101b 1024 413 2 479 03 CHEM I~HYS LETT 294 996 402 2 477 04 GEOCH LM CO SMOCH ACTA 014 744 301 Z 471 05 rlT:; El lblo 1::: 756 2 455 06 ;0s 473 277 2 454 07 TETRAI * There ~a5 an error in the numbers given in COIS.5 and 6 Of this fi~re for Accounts Chem Rcs when this article was originally published in ~cience. The error has been corrected in this reprint. 539 this distribution has shown that the ournal’s citation history, binding and typical cited article is most heavily cited ‘etention schedules can be rationally during the 2 years after its year of xtablished journal by journal, rather publication. (In any given year, 21 to than for groups of journals (31). An- 25 percent of all references cite articles other application, which harried li- that are 3 or fewer years old. ) There- brarians may welcome, is the correla- fore, since my sample consists of ref- tion of data on citation frequency and erences made in i969, I have taken as mpact with subscription costs. Such a the items-published base for each jour- correlation can provide a solid basis nal the number of items it published !or cost-benefit analysis in the manage- during 1967 and 1968. To calculate an ment of subscription budgets. impact factor for each journal, I di- Individual scientists also face the vided the number of times 1967 and problem of selecting journals to read 1968 articles were cited in 1969 by the and keep, as well as compiling refer- number of articles published in 1967 mce and reading lists for themselves and 1968. Martyn and Gilchrist used and their students. Although each of a similar method in ranking British the relatively few journals that are very journals in an analysis of 1965 SC] useful in a given discipline or specialty data (30). may be well known, it can be dit%cult Figure 8 shows the top 152 of the to gauge the merits of the other jour- 565 most frequently cited journals nals in that discipline or specialty and ranked by impact factor. Many of the to decide what journals to get and how 152 journals do not appear on thk long to keep them. It should be noted, high-impact list; in fact, only 75 jour. in this connection, that analyses of ci- nals are common to both lists. It will bt tation frequency and impact factor can interesting to observe further change: be tailored to the specific interests and in the ranking of the most frequentl) requirements of individuals by re@rict- cited journals as calculations of impac< ing the number of citing journals to a factor are extended to 1000 journals small group of familiar titles. Thus, and eventually to the approximate) with a list of the ten or so most fr- 2400 journals now covered by the SCI, equently cited chemical journals (CW merely ten journals favored by a par- ticular chemist), one can, by construct- Some Applications ing lists of citation frequency and im- pact factor, gradually augment the The results of this type of citatiot small group and the citation data base analysis would appear to be of grea with journals of demonstrable relevance. potential value in the management o] I am using this technique to establish library journal collections. Measures ~ a list of journals for the proje~ed So- citation frequency and impact facto] cial Sciences Citation Index. should be helpful in determining tk Editors and editorial boards of sci- optimum makeup of both speciaf am entific and technical journals may also general collections. Analysis of th~ find ci[ation analysis helpful. As it is, chronological distribution of items citec those who formulate editorial policies can serve as a guide in determining th have few objective and timely measures optimum size of back files, and, sinct of their success. A wrong policy, or a the data give a detailed view of eacl policy wrongly implemented, may have 540 serious effects on revenue and prestige, search? Does the fact that Eco/ogy, for and the work of regaining readers and exarnplc, cites more than 500 difierent reputation can be difficult and expert. journals in a total of 1000 references sive. Editors can find useful indicator! make it more multidisciplinary than of a journal’s performance in the extenl the Jommd oj the American Chemicaf of self-citation, the number of times Socic(y, which cites only twice as many cited per year, and the distribution of journals in ten times the number of citations among citing journals withir references, or than Physical Review, and outside the specialty literature. which cites only 600 or so journals in Perhaps the most important applica. 15,00tJ references? Does the nonlinear- tion of citation analysis is in studies oi ity of publication and citation distribu- science policy and research evaluation, tions among citing and cited journafs Price has shown how citation data can confirm beyond doubt only that rela- be used to identify research fronts (25). tively few journals are primary nodes Soviet information scientists are using in the communications network, or citation data to evaluate the implemen- does it have some other significance? tation of science policy in the U.S.S.R. And what is the significance of a wide ( 12, 14, 32), and the sociological stu- disparity between the number of jour- dies of Hagstrom and others (33) give nals cited by a given journal and the convincing evidence of the utility of this number that cite it? Eco/ogy cites 500 approach. or so journals but, in turn, is cited by only I 15. What does this say, other Unanswered Questions than the obvious, about ecology and Ecology? Is the applicability of work The data reported here suggest many done in ecology and being reported in avenues for further study. What, for ex- Eco/ogy much narrower than the in- ample, is the significance of an ab- terests of ecologists? normally high self-citation rate? Is it Several investigators of problems in characteristic of parochialism, eccen- science policy and science management tricity, mediocrity? Does it indicate are already using the SCI data base to that a particular field of study has as explore such questions and many oth- yet no basis for interaction with other ers. Each is trying, for different reasons, fields? Which is true in a particular to build a model of the journal com- case and how does one go about finding munication network that will provide out? Iilore functional definitions of disciplines What is the significance of a wide, and specialties, that will make it pos- multidisciplinary spread of titles cited sible to define in detail how different in the references of a given journal or fie!ds of knowledge interact, that will group of journals? 1s it a measure cvf provide methods of predicting inter- multidisciplinary activity? If so, is it a disciplinary impact, and that will per- vu]id enough measure to warrant apply- haps provide more effective ways of ing the Weinberg criterion (34) of monitoring research performance. Using multidisciplinary impact in order to de- the SCI data base to map the journal termine the amount of government sup- communications network may contnb- port merited by particular areas of re- utc to more efficient science. 541 Rdestmees arid Ncbt#s ten&msii i momcdcovaoiia nauchnOtckhni- 1, P. L. K. Gross and E. M. Gross, College cheskogo pr&re&P (Use of mathematical libraries and chemical education, ScImce 66, methods and electronic technology in analysis 385 (1927). of trends and in forecast of scientific and tech- 1. S. C, Bradford, Documentation (Lockwood, nical progress), In: Anofiz ?enderusil i Prog- London, 1%3), 2nd cd. nozirovanie Nauchno-Tekhiiicheskogo Prog- 3. E, S. Allen, Periodicals for mathematicians. vessa; Primenenie Matemaficheskikh Metodot EVM v Isdedownikakh PO Istorii Scirnce 70, 552 ( 1929). Nauki I 4. P. L, K. Gross and A. O. Woodford, serial Tekhniki (Trend Analysis and Forecast o! Sci- hteraturc used by American geologists. Scwnct. entific and Technical Pragress: EDP Applica- 73, 660 (1931). t ion oj Mathematical Methods in In vestigat ion.% o/ fhe HisforY o~ Science), G. M. Dobrov, Ed. 5. R. H. Hooker, A study of scientific perimhcals. ( I#dateI’s[vo Naukova Dumka, Kiev, 1%7), Ret Sci. in.strum. 6. 333 (1935). P 5-25. 6. H. H. Henkle, The pcriodlcal literature of 13. R. S, Gdiarevskii, Z. M. Mul’chenko, A. T. hlochenlistry. f3u//. Med. Lib?. AM. 27, 139 (1938), Terekhin, A. 1. Cheryni, “Opyt izycheniia Sci- ence Citation (Experience in study of 7. H. H. Fusslcr, Characteristics of the research Jndex, ” hleralure used by chemists and physicists m he Science CiIaIton Jndex). In: Prikladncua Ihe Un!ted SIaIe>. Libr, Quart. 19, 19 (1949): >okumenfalisfika (A pplird Documen talion), V. /. NaJ!mov, Ed, (Akadem]!a Nauk SSSR, Ibid.. p. I 19. ‘4aucbnyI Sovet PO Kibernetike, Seri!a Organi- 8. C. H, Brown, Scientific Serials: Characfert~tlcs !atsi ia i Upravlenie, Izdatel”stvo Nauka, Mos- and List of Mo$f Cifed Pubhcariom In :OW, 1968), p. 32-53. Muthematic$, Physic.,, Chrmi.$try, Geology, 14. Physiology, Be/any, Zoology, and Enrw?wlcmv, 4. A. Korennoi, Indeksy nauchnykh ssylok; ACRL monogr;iph No. 16 (Assoclatlon of Col- Itkh primenenie v naukovendenii i informative lege and Reference Llhrarics, Chicago, 1956). (:Indexes of scientific references; their usc in 9. (a) R. C. Coile, Periodical literature for elec- Ihe science of sciencx and in information sci- mce). trical engineem. J. Dor. 8. 209 (1952). 1 Nauch-Tekh. ln}ovm. Ser. II No. 10, 3 (h) T. Barrett and M, A. Barre It, Journol$ I:1968). mow cited by chemists and chcmtcal cngnncel ~. 15. A list of articles that have been cited very frequently has been publisked: E. Garfield, J. C6em. Ed,,,. 34, 35 (1957). (c) R. E. Btlrl:m, Citations m American crw! “Citation indexing, historio-bibliography, and the sociology of science.” In: nmnng Journals. 1. Chemical englneernng. Proceedings of the Third Intrmational Congress o/ Medical Amer. Due. 10, 70 (1959); II Mechanical en- Librarmnship, A mstmdam, 5.7 May 1969, ( Ex. glnecring. ihtd, 10, 135 (1959); Ill, Mctallur - cerpta Medlca, Amsterdam, 1970), p. 187-204. gtcal eng)ncernng. thid. 10, 209 (1959). 16. For example, in 1951 the lournal oi Biological (d) R. F. Trtmble, The murnals of Inorg.m]c Chemi.frry (JBC) published an article by O. H, chernmtry. J. 542 xelective dissemination system. 1. Chem. Dor. it Were pmssff to mnstmct aII -pfabk 7. 141 (1%7). cfaaaifh(ion that wndd accommnhte aff 22, E. Garfield and G. S. Revesz. Ten years of nf S& diiferent kinds of pubfkrdwf material. synthetic chenl ical literature; a WUistical M- it woufd have been impnasib~ for ~, ~i~ alysis of Jndex Chemicus from 196f&l 969. the rexources avaifable fOr tfd~ a~ic~, to Nature, in press. have examined indinduafJy each of the ap- 23. J. L. Wood, ‘The parameters of document proximately &30,tN30 items that I use for the acquisition at Chemical Ahatracts Service. ” items-pubfished baae. If such a difTenmtiation paper prexcnted at the American University among kinds of material were included in an Eighth Annual Institute of In format to” StOr. M Wxis such as this one, it is reasonable age and Retrieval, Washington. D.C l&17 to assume that kad articfes in such jnumafs February 1966. as Science, Nahtre, Lance:, and Journal of 24. C. Scott, The science of science; wbm scien- the American MedicaJ Association would, aa tists read and why. Discovt’ry (March 1%9), P. a =OuP. have higher impact factors than 110, those that are shown for these joumafs in 25. D. J. D. Price. Networks of scientific paptrs. Fig. 8. .Scirncr 149, 510 ( 1%5). 29. The percentage (in terms of Iotaf citations) 26. — Citation prac[ice. .4slib Proc. 21, 328 of citations of items that are 3 or fewer years ( 1969).’ old has been. for the years 1%4 to 1970, 3f,09, 30.24, 26.W. 25.91, 25,32, 25.18, and 27. The Impact factor discus~d in this arltclc 23.95, respectively. It is interesting to note (average citation rate per published item) that the yearly percentage of such items h= gives some idea of the frequency with which gradually decreased as SCl coverage has in- the ‘“average”’ pafwr in a particular Journal creased. while [he citation rate per cited item is cited. The factor is, of courxe, adversely has gradually increased (19). The significance affected by papers in thejournal which are of these trends is an interesting matter for not cnted at all, and, as noted above, favor. future investigation. ably affected by papers cited with unusual 30. J. Martyn and A. Gilcbrist, An .Evahmrion of frequency. Tbe mtluence of uncited and very British Scientific Periodicals. Asl ib Occasional frequently cited papers can be discounted by Publication No. 1 (Ashb. London, 1968). considering the total number of citations in 3 I. (a) D. MacRae. Jr.. Growth and dccav curves relation m ctted Items only (rather than m in scientific citit ioris, A mfr. SOcio/. iev. 34. relation to all published items), or by con- 361 (1%9). stdertng only numbw of cited items (rtilher (b) R, W. Chadwick and K. W. fkutscb, Dou- than total citations) in relation to all pub- bhng lime and half-bfe: two suggested con. lished items. For example, if tbe items- ventions for describing rates of change in publisbed base is IC43 articles and one artick social science data A mer Behav. Scirnti.rf 11, has been cited 50 Ilmes while W articles have NS9(I%8). not been cited at all, the impact factor wuuld l?. (a) V. V. Nalimov and Z. M. Mul’chenko. be 0.50. The same impact factor of 0.50 could Noukomctriia (Scienfomrtrics), ( Izda!el’stvo he derived for the journal that bad half of its Nauka, Moscow, 1969). 100 article% cited only once and ttw other half (b) L. N. Beck. Key issues in Soviet in forn>a- not cited at all, If one conyders only cited tion. J, Amer. SOC. Inform, Sri. 22, tt5 (1971). items, a per-cited-item impact factor can be )3. (a) W. O. Hagslrom, Inputs, outputs, and the derived to distinguish hstween the two I,mr- prestige of university science departments. nals. fn tbe first case, the f-er-cited-item im- .%ciol. .EJuc. U, 375 (1971). pact factor would be 50.0; in the second, (b) A. E. Bayer and J. Folger. Some corre- 1.0. If one considers onfy the number of cit- lates of a citation measure of productivity in able items cited, a citable-items-cited impact sciences. Socio/. Educ. 39. 382 { 1966). factor can be derived to further distinguish [c) J. A. Creager and L. R. Harmon, On-lhe- between the two Journals. fn tbe first case, tbe Job Validation ot .Wtction Variables. Tech. citable-items-cited Impact factcw would be 0.01 ; Rep. No. 26 (Natlonaf Academy of Sciencex- in tbe second, 0.5. Enormous amounts of com- National Research Council. Washington, DC., puter time would he required m derive these 1966). different impact factors, although one must (d) S. Cole and J. R. Cole, Scientific output acknowledge their potential usefulness. It and rccognitmn; a study in Ihe operation of should be noted also that eitkr of tksc im- the reward system in scwnce. Amer. Sociol. pact factors can he derived fr$>m lhc’ other hy Rev. 32.377 ( 1967). dividing one t>f lbcm mlo Ihc tmpdct f.ILtur (e) E. B. Par’ker. “W. J. Paisley and R. Gar- used in tllis artlc!e. rett, BJblmKrapbical Ci[of#on.s as Unobtru$tvr Meawmc.! of .ycientlfic Communication. ( lnxll - 28. The problem of selecting an items-publkshed !ute for Communications Research, Stanford base is further complicated by the variety in University, Stanford. Calif., 1%7). the kinds of items pubfished in scientific (f) J. Margolis. Cltatlon indexing and evalu- journals. Many journals pubfish only fuU- ation of scientific papers. Scwnce 155, 1213 Iength reports of originaf research. Many (1%7). others pubfisb, in addition, editorials, tecb- (g) J. Larabi, Mesure de I’efficacite des lahor- nicaf communications, letters, notes, general atoircs de rechercbs fondanremde xelectionnes correspondence, scientific news surveys and par Ic Centrc National d’Etudes Spatiaks. Rev. notes, book reviews, and so on; all of tbeae Fr. In/or#n. Rec6. Opera:. 3, (No. V-3), 103 are potentially citabk items. I have not at- (1%9), tempted in this article to limit the definition (h) D. J. D. Price, Measuring the size of sci- of items-pubf isbed to lead arficks, original ence. Proc. J.srarl A cad. Sci. Humanirms 4. 98 communications, or the like. Even assuming (1%9). 543 (i) R. D. Whitley, Communication nets in aci. (n) J. P. Martino, Citation indexing for re- ence; status and citation patterns in animal search and &velopmem management. IEEE physiology. SOciol. Rev. 17, 219 ([%9). Transactions E.g. Management EM-1$, M6 ti) s. CJ3k profession.d stantitng and the re. (1971). ceptwn of scientific discoveries, Amer. J. (o) Anyone interested in citation analysis in SocioJ. 76, 286 ( 1970). study of Ihe hhlory and sociology of science (k) C. R. Myers, Journal citations and sclen. will ‘find the following biMiography invsduabfe.: titic eminence in contemporary psychology. A. Pritchard, Statistical iSiblio8raphy-A n Jn- Amer. Psycfd. 2S, 1041 (1970). terim Blbllography (North-Western Pcdytec.hnk (1) H. Rothman and M. Woodbcad, The uac Schonl of Librarianship, London, MaY W&J). of citation coumin~ to identify research trends, Available from the U.S. Department of Cm& J. f)OC. 27, 287 (1971). merce. National Bureau of Standards, Ckar- (m) J. Cole and S. Cole, Measuring the qual- inghocme for Federal Scientific and Technical ity of scientific research; problems in the usc information. of theScience Citation Index. Amer. Sociol. 34, A. M. Weinbmg, Criteria for scientific choice, 6, 23 (1971). Mincr~a 1. 159 (1%3). Reprinted from Science 178:471-79, 1972. 544 Febmary 7, 1973 . For more than a year I’ve beersciting what ‘impact’ of a much longer list of journals. As a I consider to be one of the most significant result, we’ve determined that certain ‘small’ papers I’ve ever published. At long last it has journals that publish relatively few but very appeared. 1 frequently cited articles deserve to be included The paper deals primarily with the use of in the coverage of SC1and CC our Journal CYrz?th Index data bank to deter- For many years, we’ve included review mine the frequency with which scientific and journals in SC1 and CC and our studies show technical journals are cited in the journal litera- we were right to do so, Although few are ture. [t shows that a ‘large’ journal that pub- among the most-cited, several are at the top of lishes many articles is, as a rule, more fre- a list ranked by impact. However, review jour- quently cited than a journal that publishes nals are very expensive to process for SC1 The fewer articles.. In addition, however, through average review article contains from 3 to 10 development of ‘impact factors’, it shows that times the number d references as the typical articles in about half of these most-cited jour- research article-some contain as many as nals are cited less frequently than articles in 21XKIreferences! This must be taken into ac- smaller, less-cited journals. count when selecting journals for the SC1. It is Regrettably, the editors of Scierr% where less important, of course, for Ci2 the paper has been published, could not give 1 hope it is obvious that we take the space to include the originally submitted list of question of journal coverage very seriously. 1S1 the 565 most-cited journals that are mentioned has devoted enormous time and energy to find- in 75% of all references published. But we ing objective criteria for journal selection. Un- intend to make this list available, and will fortunately, the objective criteria alone don’t update it sometime in 1973. The list of 152 solve the problem. There is more that we feel journals that appears in the article is now three should be considered. Readers frequent 1y re- years old. commend that we cover journals that, for one It should be significant to our subscribers reason or another, show up poorly in citation that all of the 565 journals mentioned abovc- studies. It would be courting disaster to ignore indecd almost all of the 1000 most-cited jour- all such recommendations the basis of cita- nals—are covered in either the science Citation tion data alone. In the process we might deni- Indexor in ClrrrentContents grate the just motives of those who strongly Since completion of the work repwted in support CC, whether from professional self- the article, we have been able to measure the interest, national pride, and so on. All such 409 decisions are acceptable provided that we dili- ans especially expect a continuity of coverage, gently make certain that the best is always but sometimes rhe facts of life require that we included. weed out journals that no longer ‘cut the mus- Every year we go through the painful tard.’ Retaining a mediocre journal means budgeting process that determines, among omission of another, better journal. We are a other things, how many journals we can add to long way from zero population growth ofjour- each 1S1 service. It’s plain that some readers nals. In fact, older journals not only survive, imagine we can and should cover any journal but the hard core grow in size. Their growth in that comes to our or their attention. Some seem articles published almost equals the number in actually shocked to learn that ISI is not some new journals. These journal dynamics are prob- sort of inexhaustibly funded quasi- ably a healthy phenomenon in scientific governmental agency. To expect that we cover communication. any and every journal is almost as unreasonable If, in spite of all the hocus-pocus about as our own fervent wish that every scientist in journal selection discussed here, you feel that a the world subscribe to CrmrerrfContents. This particular journal is improperly omitted from might make it economically feasible for us to CCor from SCI, please let us know. But don’t cover almost any journal, even if space did not fail to tell the editor or publisher of thejoumal call a bait at some point. as well. We’ll always be responsive to readers’ Once we have established our annual bud- sugg~tions, though we must hope that you and get for journal coverage, we are invariably he will appreciate the economics as well as the approached by some journal publisher or editor ‘art’ of journal coverage. who wants some new journal covered immedi- ately, What are we to do if the journal meets all important editorial requirements for selection? 1. Garfield E. Citation analysis as a tool in We can either tell the journal’s sponsor to wait journal evaluation. Science 17847 1–79, 1972. until next year, or we can ask him to under- — In early citations of the article, I used the write coverage ofhisjournal in order to help us title on the MS submitted to Science “Citation live within the budget as we must, analysis as a sociometric tool for journal evalu- [t is never easy to drop a journal once it ation and science policy studies. ” Reprints are has been added to Current Contents. Librari- available. The article cited in the reference above is reprinted in this volume beginning on page 527. 410 BmprLated from Scmm, JolJ lb, 1953, VOL 1% No. 3159, p- 10S-111., - Classified indexca are ako dcpmd- em upn a subject analysis of individual artickl and, at buf, olkr u better CO.- iseency of indexing rather tba” greater Science .pecfiuty or rnukiplicit y in fbc s.bj cct Citation Indexes for approach. Simdarly, terminology i, im. portant, but even - ideal .tandardiza- A New Dnenaion in Documentation tkon of terminology and nommclat.m will not solve the prc.bkm of SUI+CL through Associationof Ideas Vmaly!k What*enu to Ix needed,then,in ad. didc.nto teue? and more comprebcnsiv. Eugene Garfield, F%.D. indexes, alphabetical .“d clmsified, .,. w types of bibliographic took that can help to spa” the gap b@#een the wbj.cs ~ppmach Of [hmc wbo create dacumenu “The uncritical cifation of disputed app~ch,- fibject control cd the Iitc,a. —ffut is, a.thors--and the iubj.ct ap databys writer,whctbcxit be dcfibmatc ture of scwncc. By virtue of its d< flerem proacb of the scientist who weks irdor. of not, u z serious matter.Of come, construction, it ten& to bring together mation. knowingly propagandizingunwbstmti- material that would never be collated by Since 1873 the legal profession h~ awd claim “u particularlyAborrcnt, tie umal mbjcct indexing. It is best de. been provided with an inval”.bk re- but just m manynaive studentsmay be tcrifud .s an a-i.tio”+f.ideas index, ward tool kmwn M Sh epo ,.4’s Citd icwu, swayed tq unfounded asscrtims PK. and it giv- the reader M much leeway fmblisbed by Shcpards Citations, Inc., Icntcd by a writer who is unaware of the as he rquira. Suggestiveness through Colorado Springt, CA. (2). A cilatio” criticisms. Buried in scbolarly jou ma k, association-of.ideas u .ffercd by conv.n- index u published for court cases in the critiml notes are increasingly fiiely to lional $ubject indexes but only within the 48 stat.a as well as for .a%s in Fedcr.1 be overlooked with the passageof !imc, Iimiu of a particular subject heading. courts Briefly, the Shepard citation ~ while tht smdi.s to which they pertain, If one comidcm the book .s the rnamu tern is . listing of individual American having ht.” reported more widely, are unit of thmght and the pcri+ical article cmrt casm, each cam Lxi”g fd lowed by apt to lx rediscovered;’ (i) fhe micro unit of thought, then the cita- a complete history, written in a simple tion itidcx in #ome respects dmls in !he cede. Under c?.ch case is given . record In thk paper I propose a bibliographic s.bmicm or molecular unit of thought. of the publications tb%t have referr,d m systcm for Kim.. literature that can 1! it here that most indexes arc inade- the case, the other court dcckiom that eliminate the uncritical ciLali.n of ha”. quate, because fhc scientist is quite often hzve affected the case, a“d any other duknt, incomplete, or obmk[c dam by conccmed with a particular idea rather rc{emncei that may lx of V-AC to tht making it pmsibk for lIu comcicntio.s dun with a cornpfetc concept. “Thought” lawyer, This fypc of listing is partic”- ichokr to be aware of ctkicimu of indexes can be extremely useful if they kdy important to [he lawyer, bcca”se, eartkr papers. II i$ ton much to expect a are properly mnceived and developed. in faw, much is based .“ preccdcnt research work. r to spend m i“ordinat. lrI the literal. re-scarch,”g pro.-, i“. Citation indexei dcpe”d on a simpfe amount of tirm s.archtmg for the b!bfic- dcxcs pfay only a s“dl, although si~nifi. system of coding c.tries, one &at m. gr.ph,c d=cndants of a.1.,edmt p,. .s”1, part.‘flowwho %ck ccwnprthciuive q.,r= mi.im.m $Pac, a.d fac,lita~~ Ihc pm. It would not & excessive to de- ittdcxu to ihe Iitem[ure cd scicncc fail to gathwi”g together id a ~rcat volume of mand ihat the thorough scholar check point OUtthat m.h ind.xc+ .Ith..gh ,h.y m.ler ial. However, a mxfe is “or abm. all paptm that hzve cited or criticized may & desirable, will provide only a lutdy necessaryif one choosesto compile such pspcrs, il they cmdd be located Mt.. ,t.rtmg POI’IM thm (he one prm . Wwm.ti. listing of i.div,d.al cas.s or q.i.kly. ~,. citation index rnakcs hi% vialed i“ the wlcctive i“dcxm at prmcm repao, with a complete bibliographic check pract,c.bk. F.ve. ii there were “o available, Om of the basic diffic”l[ics u history of each of thcm. Tb.s, it would other use for a citatim index lh.n du( w build wbjcct i“dcxcs that c.” antici- b+ pimible 10 list all pertinent refmm.c of rpinimizing the .#tation O( p.wr d.ta, pate the infinite n.mbcr of pos.,bk ap tinder each cast, with sul?icicnt mm. the index would b. well worfb tic clfort proack the scimtist may require. Pm. rquircd to compile il. poncnts of classified indexes may suggest Lh. Garti*ld1. DIMCIO, of the 1..,1,.,. Thii pa~r considem the pihlc util- thatclassification u [he mlution to t~t, 10, Scmn,ltlc I“k.mtlm, 3$ south 17* ily of a citation ind.x lfut OKcm a new problem. but this is by IW rncam the 8,,..,, Ph,l.d.lfi,m 3, P.. 2 plcwncss to give the index m.re of the wcmld be listed other code numbm rep- cbercfore paenthllyfrom 50 10 100 A~pa rance cd a bibliogmpb y, Hm+wvcr, resenting mticla that had refrrrrd to the timu u great u it U for k’k~pd’l Cita- [hu would re$ult in m extremely bulky article in qucsti~ tcgether with mt in- 1km,. volume. dicdan of whether the citing wurcc ffowcvlr, not lff of these 50,000 pub There are analogict fn bildiiapMc was an original articlq review, abstract, ficaticmt arc being covcmf in our present o~r~tions. For example, in catahging * mticfq patent, or tmnsfation, and indexing activities, and yet tits has Ml books [or fmobeflcrd a? library cadogs, m forth. III c?lecf, the SYWCIIIwould pl’O- ptevcmed us from continuing indexes O( miawctnpt is made to find refcrenca to vide a complete fiiing, for the ~blica. standard type or fmm starting new ones. each bmkinonea more aatboritative tions covered, of .11 the original ●rticlci Lick of complete coverage u not rKCCS- bibfiiphic soumei, & u tbdcata. that had referred to the aniclc in qtws- mrily M mgument against * citation in- ~s.( the British Museum ( BM), Biblio. tiom This would clearly b Pmticularly dex. II u in fact ●n argument in iti favor. dt~que Nationale (BN), ortbc Library IAIChdin hutoricaf rrscarch, when one it (lwcrage could perhap# be fimited to the of fhtgrcm (Lc). TIM”autbority’’ard Uying ta tvaluate the ti~ificaiwe of a fist of periadkals covered by one of the wed in cataloging wmetima fooki fike fmrticular work and im impact on k leading indexing -ice% TIIU approac& 1 F&pad entry. fitct-ature and thinking of die period. wo”fd, of course, have an immediate d% Anmber lxflmp]e u 1 bwk-review d,- Such UI %lFUCt fSCtO#’ lluy k UUKb advantage, Such a wbjw selection gat, kn wMcb one finds for each book more indicative than ●n absolute count would mean that laY dircaty related mib tide s W& of refcrmccs and selections of the number of a scienthth publb- jecu of interest would be excluded, and Imm published tiews, crkical ●nd tions, which wa9 used by L&na” (3) these arc the publications that the indi. othetwise. Certain indexing pubfiations and Dennis (4). The ‘Impact factor” h vidual is least likely 10 cover in his own pcri4rm ● dmilar funckion. similu to the q.aotituive mcamrc & r~mh. It would be necessary to con- Some time ago I became concerned taincd by Gross (5). in evaluating tbe sider all the pi-us and cons in a tefcctive with the problem 01 dcvelopi”g a cita. relative imptance of xientihc jounuk, ~,pp-ch and the. co determine the pm. &an code for ackmc. Thii wat mcesa~ a method later criticized by Brcdman sible utility of such a tool. For aampfc, for the etlicknt manipuhtioo by IIUChan. (6) fut used again by Fwlcr (7). would a citation index to the 15CLlperi- id dtica of cntria to tientific indaes. Other advancagct would atw obtain. odical coverrd by the Curwti Lid 0/’ [a die counc of this research 1 developed Ins way such liwingt would pmvidc each .44tdicd Litrmfum be ofrealvalue.or, a vw simple system for identifying an xientist with ●n individual dipping sew- similarly, ● citation index to the 5@J0 indhidud 8cimtific article that had ap- ice. By referring to the Iistingz for hu pcri.xficafs covered by Chemicak Ab. parcd in the pcriackaf pm. llu re- aniclc, d author could readily deter. It,lICtl? The Curwnt List would, in fact, wlting numerical code comistaf of IWO mine which otk acicmdsu were makiig offer a good starting point, since it af- parts. ‘h tint part wat a serial n“mbcr, mfercnce to ti work. thus increasing ready provid= a unique code for the used instead of an abbreviation, to iden- communication possibilhiu between aci- IIXWIO items indexed by it each year. tify each periodical; it w simitar to the entista. It is afm possible that the in&- Presumably theseare the most significant serial numbut employed im the World vidual Kicntim thus might bcconw aware contribution in the ccwercdfield$ for die fit Of Scuntific Pe,iodicafa, by no means of impficatiom in his studia that he was year. If IO is the number of rcferencez in ● new idea. For ma mplq Du BibJie. not aware of before the average article, then atit 1 million gmphit dtr /rtmdsprachigea Zri/mhri/. Meet authors Iikc to w bow lheir citaticmi would be involved. The preps. tca Li:ma:ur has for many yean wed works ● re received, Bringing together all ration of that number annually is M un- tucb a ~ent to save space. kook reviews and abstracts is VW im- reasonable. Shepardi has already used The second part 01 the code mmtbcr portant, for i! it not postible for an well over 50 million citationa in itt pub- WM dm a serial munbcr, at+md @ each author to keep up with the tbousanda of fisbing ●ctiviticm udcle in . pmtic”l.r publication, start. pub ficmioiu i“ which hi, contribution TIM “Idmate access of a citation in- ins with I and continuing thmugho”t all might be reviewed. This appliu qually dex would depend O. many factors. For volume& Tle code thut gives M indica. @ publisfwn. h would not be im~ib[e example, if QCII periodical wouId assign don of year or volume numbm, a Know w include kooks in the cimtion index. In- unique code numfxrs to the articlu pub. abortcorning. The udc!e number i, ●tso deed, u a fimt suggestion, lbe .ie of IMA, it would be ~ibfe for authon em umiq”e, having been used by the Pro. Library of Gngrcit card numb u the 10 list that numbetx in their bibliogra- cetdine: of the $ocitty @ Exp,rimtntak identifying c.mie for bcoki would seem phic! ●nd, thus, 10 save the work of md- ● Biology nd Mcdicinr timx itt inception. appropriate. iW,On the part of tbe citation index WSff. These two serial numbem tab together, It ii nccewary next to diacun $omc It u wilskely that mb a dcvelopmmt it can be wen, can idcmify any published realistic qustiont concerned wib rhc could take place in lea! !ban 5 G+ 10 periodical article h soon Lmtamc appat. mfiition of tuch an index. Bitner (8) year!, but it it comparable to the problem ent, ●fte, tuch codes had been utilized on has estimamd that SO,(XM cases arc cov- of getting pufdidmz to include Librmy an experimental kusi%that the use of the ered by Shcpard’~ Cifdiow III 1 year, of Gngr- cm-d numbcn in their pub codes would t.tifitatc the compilation of the ca~ -d article appearing in not Iications. . citation index. ( Chher coding sys(ums more than a few h“ndrcd publicmions. When such a large volume of data is would be equally ●ppfkable. ) In 1953 about t milfion citatiom were to be handled, mechanical devicu of A citation index to science would have added-clox td 40 citations per case. high speed and vcmatifhy coufd be used the following main characccnstics. Fwst Whzt is the prospsc{ in scientific liwra. m greai advantage a“d would probably there would be a complete alphabetic lure? The latt publidted cditicm of the determine success or failure. ChICC the listing cd all periodicals covered, in ad- World tit of Scicmifc Periodicals mm- ccdng is done, compilation iuelf u quite dition to the code numbs for each P-. uincd more than 50,000 !itlcs in scicncc mechanical. Tbi$ could be done by means riodt.al. The Itsl would be similar 10 the and technology. It is varioudy c$tirnawd of conventional filing di~, the Shepard Worfd .LMI.but without the library hold- dial between I and 3 million “at’ scien- organization itself ha, used than IUCCUS. ings in fonnauon. The main porlion of tific anicley are published each year. The fully for W years. However, it would tM the c,tation index would list in straigh! /otird of /h/ ,4mmicam Choni.d So. facilitated by a mechanical approacfI numerical order lhe code numbcm for all cicty aloife p“blkbcs more tbm .SOtKIp using p“nchcd cardx the anicl es covere& U“dcr each code Year, including approximately ‘NOO origi. The utility of a citation index in any “umber, for example, 9001.6789, them ma! ●rtwks. The order of m.tg”itude is field numt ●lso IM considered fmm tba 469 a point d vinu of he tranmimion,01 rn another imtamce the RCA ariicle adaptation sy”dmmc ( !4 ). A syst.mmic idrw. A [hmm,gh scientist cannot be ,.m ““cxpecmdly cimd in the jo”mal scafi was then made of =11papcr$ that satisfied merely with tcarching fhc limra- Electronic Enginrevisg in an article cm were pubfished in the ]our..d of Clizwal ture through indcx,~ and bibliographic< i“lurm ation thm~ ( 12) that I w- mad. Endoc,inoiogy subsequent to S+’s if be u going to mtabfish Ilk history of i“~ bccausc of an entirely ditfercnf in- paper up to 195l—a period of 5 years, ●n idra. 1Ic mu$f obviously da a grat terest.No wbjccf indexer could have an- i@idt”g well over 500 articlv. Every deal of organized, as well m cclcctic, ticipated this crosdmeding of intecests. bibliography in each of the 5fsl mttcles read,.g. The latter is ncces.wy bccawt I%rhaps there arc many other mficles waJ checked for a w f.xc”ce to Sd ye’s it is impossible for any one person ( the a“d books unknown to me that have mficle, Twenty.three ●rticles we;e found indexer] to anticipate all the thought made ,imikr rcferc”ces to his dcvicc. to make such reference; each of them processesof a wer, Ccmvc.ti.mml subject 1fow can they be located whm the main was !hcn checked for the character of indexes ● e th.mchy limited i“ their ●t- $ubject matter of fhe article i!, on the the information pr.avidcd. tempt to pmvidc an ideal kcy to the lit. .IIrtacc, 10 .nrclatcd in nature? Eaatnination of the citation list (Table erature. Tfw iame may be mid, of clari- One might say that it would be P I ) showsthe great variety of subject mat. fication scheme. In tracking down the sibk to index articles “ore thoroughly ter incl.dtd. O“e thing became quite origiru of an idea, the citation index @n m achkve the same TMI1!S, For camnple, clear, Wen to 3he uninitiated—tba.t is, the be of real help Thi, is well illustmtcd by the article .“ i“fmmaticm the.my, ir thcw- influence of Sely/s article ha, bee” quit. an example from my m+’” Cxpcrie”ce. oughly i“dcxcd, might h=vc i“dudcd m pronounced. Such evidc”ce is wdrmnd y Many ycam ago the Radto Capomtion e“wy “mder reading dcvic” for the bfiwl valuabfe m rhe himriam of Arncrica dcvdcqxd a wading.aid for Yet if thit were done, o“r periodical in. It is intcrmdng to note that, aldmugh the blimf (9). This device had . . elm. dining scrviccs would clearly bmomc all 121earticl” cited were i“dexmf ,. Ironic system fur mnvcrting printed fet. hopclcmly c.verloadcd with material that Q.a,tdy Cumulative Indtx Med,cw, ten into recognizable sound patterns. is “.1 nccessaty to lead .3 IO the micro not one is to be [o””d there ““din the Using the dcvicc, z blind tin could ,can unit—the entire article or one O( iw heading “Adaptation.,, In fact, it is s“r. * printed page; in . WI of hcadpho”cs major scctiom. Although it might be =id PriSing not to find any articles from lhi, he ccmfd hear a terics cd sound patterns, tha! no scientist i“terestcd in the greater ]o.rrul under this subject heading. each Ictt 470 4 Is. Recant, L., ;1 d.: l!f?cct cd Epinc- sented indicdts9 that the citation ink fbe citingankle andthe codefordie Dhrinc on Smincmhifs. 10: 107-226 &m interesting possibilitiu for UUMIW bet (its LC cardnumb). i1930). - approach to btbliosraph ic control. After dl the articles had been codd McArthur, J. W., d d.: Urinary The next Wp in’ compiling the index it would next be nccmry to son tht Escrction d Cktic.mwmids in Dfa. for the Rely. article would be 10 $eekout carcfi by the code n.mbcm (or the items betic Acidmifi 10: S07-312 ( 1950). additioml references fo it in more cited. This would yield a group of card 15. Sore, E.: Fertility i. Yamplegic periph- MA,, 10: 3S1-S98 (1950). ml joumafs, but obvioudy the farther 101each citsd article. That wwld then 16. Grossman, S., ccd.: Idiopathic .k- away you set from the immcdkmc subject be totted by code mumbcm fat the citing tmiolk followingtborwpluty, 10: area of the, main article, tie fewer the ●niclu, T13iI cc.mpleteathe CA36ingand 72%J34(1950). refcrencca to it you till locite. Ye4 ** sorting. The m: step woufd be pmparz. I 7. Oooper, J. S., d d.: bfctabofic b nuy well be the mm4 useful rcfercnca of lion for khe printer. ~.em= 4 spi~ ~ MIX% IO: all, for the cross-fertilkzmioa of subject Fmm thb dacripthn it will be appar- D3s-lf70f 1930). .. fields u ons of our m-xi important prO& ent that, although a great volqne of ma- 18. Hioco, D.: Adrenal Metabcditea m Ienu in science fiterarum, !erkal u to be covered, relatively umkilled y9mcDf Altblna, fo: 157*1578 ...... II will be well to close wkb a brief penom can pmfonn the necessaryding 19. Jukr, J. W.: Pft.ilary-Adremd Sys. description of how the cicati.n imkx and filing. Profticmal w pervision wcwld tern in Lafan% II: 1sS-192 (1951). might be compiled. ‘The lint step woufd still be required, becausetimtain drcisiaru 20. Deane, H. W,: The Admmh in l!.x- bs the election of fhe particular group mquim skilled judgmrnt, for example. pcdmenmf Hypertcmion, 11: 193- of periodicals to be covered; next, fht when ibid. or foe. cif. must be cardufJy 208 (195t\...... period to be covered, say, only tfut since interpreted. Fomwtrs tend to make cod- Hiom, D., d Epinephdae and 21. d.: Iw. ing somewhat cumbersome. The cede I ACTH in Smncbhf Atthnta, 11: ~e problem aCOJdty b tWO f~CCU: have described u merely ● example wed 395-407 (1951 ). 4he selection of periodicals to lx covered to illustrate the mcthcd in principle. If 22. EchafTenfxrg, C. A., .1 d.: F-HP droxypmpi.aphmo.e ( PHP) and in order to obtain citation% and the sdec. the system .&c adopted, then in the other so-called pituitary inbibitom, tion of those articles for which we want fmure every author ought to bc required 11, 1215-1223 (1951). a citation record. For example, dl ar- ‘b incbmke[he send number of each item 23, Tdbot, N, B,, d d.: Urinary Watez- licft~ in jo.mab in the Current List o/ be referred to, so u to facilitate not only Soluble Cmticosteroid$, I I : 1223- .4fcdicdl Lifcmlure that have remained tht compilation of citation indexes but 1236 (1951). in cantin”ous publication since 1900 aka other operation$ such = requcsu for might lw coded, in wh,ch cw thr. IO.,. reprint$ (15, 16). Cil.tim lnd.x Emtvy d o/ Clinical Endocrinology would not In a certain sense ● citation index i9 11123s.687 be included. However, we might include not very di17erent from ● mm+dium 464-9789(R) as citation murcc% all jo.rnah covered like BAf,fcin, which giw * mcher com- 269-3366(R) by tht Current List. Thu$ the biblicgra. pte{e record of a compound, compiled 1105-9876( A) phiea appearing in articles in the journal by a ~milar method. A citation index 1123-4432(R) of Clinic81 Endocrinology wcmld supply for the’ literature of chemistry would un- ml1,12345752(0) references to the basic group of articla. &.btedly make the preparation of mwh .0779 (0) Sac+ coder would be assigned a group works as Beihtein much easier than ic is -7264(0) of ●licla in a particular jmmml. The at prcserw. The new hibliogmphic mc.1, .7331 (0) fir$t ncp would be to number each articfc like otbcra that alrudy e+ is jum a .7385 (o) ● .0866 (0) in !he joumd in cending order, by uarting pint in literature research. It 4221(0) utiliiing a complete table ol contenls of will help in many ways, but one dwufd -ll~ll:; 45Mtjournal km ha incepk not qect-it to mlvc all bur pmbltmi. Once a code number has bee” assigned red-. d N- -9529(0) to each article, the proper codes may 1. P, ?hom- amdJ, C StankT,S+.’. HI. then bc assigned to each pxio&cal. Thii 610(1PM).l%m!teca sndStan!” _ com- might bc the n.mbcr given in the World mn,l”~ O. C. Zirkk,t dti,m O! k _ to the rc.dcrd cnlightcnmcnt, since exact List, with new n.mbcrx for any pcriodi. .( Imud”lentdam [Se”.a la. 16P(M501. ?. W, C. A&ir, A“. D.<.”wmut8.. 6, S1 me rcfcrcnc- ~re n~~ prOvided. !n SW- cals not to be found there. , ,M. ) craf cam the SClye article it even cited Act”al co&g $tar[s with the fimt ar- 3 ii% ‘hbmm. Sri. Mmtti 74331 l195d s w. Dennis.ihd. n, 143(1954). but not rdcrred to in the text. .%-lye’: in- ticle in a partimlar periodical. The coder $. ~~1~7)C_ and L. M. Grcs, S<”... ~ fluence on all of these authors i$ quite prepares a 3- by 5.in, card for each cita- 6 ~h ;$~ Med. bbva~ Am’. BrO. 33, ●p~rcnt. ln particular .imtancu the ci. tion made in the article, Each card taoom arc of value in Iocatins confirma- should Sivc (i) tbe ccdc number for the 7. H. H, Funk,, LA.- Q8u4. 19,19 (1949). tory cb,idcnceof some of !+.’, claims. c,ting article, (ii) the cod. imrnfxr for S. lll,Shr.cr, _ co=micatim. AFAI Tlnm, in the caseof a highly significant the article cited, and (iii ) 1 classification 9. V. K. Z-ark,. ud L. E W. *w, An article, the citalion index has a qqanti. of the citing arLicle as ●n original con- Ph.nso. % 139{Itwl. 10, il. R. Sh.w, M..!4i.., .d 1A. 5,biwH.#kL tative value, for it may help the his!orian tribution, review arficlc, abstract, and IO .d Fr.blcm! ./ 14. rw..l”’h C-1.7 (u. {.. to mcamrc the influence of the article-- forth. 4 Mimi! k. Ultu”a, 19311,. 19. (n.. ● that is, its “impact factor.” With regard Many rcfcrcnccs will be cxcIuded by prhtaiIromLbbliqmph, u s A,. 4 Sch.,, (Univ. c4 lllmou P-u, Urhr-, 19X1. to ● 1.ss significant work, one would sus- the limits of covcra~e set “p. Thus all 11. R. Bum, Ncchr. Detmm,””tim S, M 11953). pect thm the bibliographic advantages rcfcrcnccs to articles not in ihc prcscrihd 13 A M. Andrew. U, flr-ic .%. 35. +71 11S53) 13 S. Gfild, ,W=”ie” I,wr.twe “ . tourmd migh! bc incrca$ed, bccau8c the scicntitl list of jogrnalt would be excluded. crhkd ..-* for scientifici*es, u+mb or I,brariam would be pmvidcd with rcf- All books would b mdudcd “nfcm * p.wr, Dccwmber1952. ercnccs not to be found in conventional othcrwim $p..ificd, i“ which cm- thr 14 II *IF, ). C14.. Ii.d. 471