White Handed Gibbon (Hylobates lar) Asensio, Norberto, et al. “Gibbon travel paths are goal oriented.” Animal Cognition, vol. 14, no. 3, May 2011, pp. 395-405. Academic Search Premier, doi:10.1007/s10071-010-0374-1. Accessed 23 June 2018. Asensio, Norberto, et al. “White-handed Gibbon (Hylobates lar) Core Area Use Over a Short-Time Scale.” Biotropica, vol. 46, no. 4, July 2014, p. 461+. Academic OneFile, link.galegroup.com/apps/doc/A397390625/AONE?u=nysl_we_caniscl&sid=AONE&xid=98782 668. Accessed 22 June 2018. Asensio, Norberto, et al. “The ecology of white-handed and pileated gibbons in a zone of overlap and hybridization in Thailand.” American Journal of Physical Anthropology, vol. 163, no. 4, Aug. 2017, pp. 716-28. Academic Search Premier, doi:10.1002/ajpa.23241. Accessed 23 June 2018. Balolia, Katharine L., et al. “Sagittal crest formation in great apes and gibbons.” Journal of Anatomy, vol. 230, no. 6, June 2017, pp. 820-32. Academic Search Premier, doi:10.1111/joa.12609. Accessed 23 June 2018. Barelli, C., et al. “FEMALE SEXUAL ACTIVITY IN RELATION TO REPRODUCTIVE ENDOCRINOLOGY AND MATING SYSTEMS IN WHITE-HANDED GIBBONS (HYLOBATES LAR).” International Journal of Primatology, vol. 27, Feb. 2006, pp. 281-82. Academic Search Premier. Accessed 23 June 2018. Barelli, Claudia, et al. “Female white-handed gibbons (Hylobates lar) lead group movements and have priority of access to food resources.” Behaviour, vol. 145, no. 7, July 2008, pp. 965-81. Academic Search Premier, doi:10.1163/156853908784089243. Accessed 23 June 2018. Barelli, Claudia, and Michael Heistermann. “Sociodemographic Correlates of Fecal Androgen Levels in Wild Male White-Handed Gibbons ( Hylobates lar).” International Journal of Primatology, vol. 33, no. 4, Aug. 2012, pp. 784-98. Academic Search Premier, doi:10.1007/s10764-012-9606-3. Accessed 23 June 2018. Barelli, Claudia, et al. “Mating patterns and sexual swellings in pair-living and multimale groups of wild white-handed gibbons, Hylobates lar.” Animal Behaviour, vol. 75, no. 3, Mar. 2008, p. 991+. Academic OneFile, link.galegroup.com/apps/doc/A175251190/AONE?u=nysl_we_caniscl&sid=AONE&xid=26208 566. Accessed 23 June 2018. ---. “Sexual swellings in the wild white-handed gibbon females (Hylobates lar) indicate the probability of ovulation.” Hormones and Behavior, vol. 51, no. 2, Feb. 2007, p. 221+. Academic OneFile, link.galegroup.com/apps/doc/A160544558/AONE?u=nysl_we_caniscl&sid=AONE&xid=74921 d73. Accessed 22 June 2018. Barelli, Claudia, and Michael A. Huffman. “Leaf swallowing and parasite expulsion in Khao Yai white- handed gibbons (Hylobates lar), the first report in an Asian ape species.” American Journal of Primatology, vol. 79, no. 3, Mar. 2017. Academic OneFile, link.galegroup.com/apps/doc/A494492157/AONE?u=nysl_we_caniscl&sid=AONE&xid=befb7d 31. Accessed 23 June 2018. Barelli, Claudia, et al. “Extra-pair paternity confirmed in wild white-handed gibbons.” American Journal of Primatology, vol. 75, no. 12, Dec. 2013, pp. 1185-95. Academic Search Premier, doi:10.1002/ajp.22180. Accessed 23 June 2018. ---. “Cues to Androgens and Quality in Male Gibbon Songs.” PLoS One, vol. 8, no. 12, Dec. 2013, pp. 1-9. Academic Search Premier, doi:10.1371/journal.pone.0082748. Accessed 23 June 2018. ---. “Is grooming used as a commodity in wild white-handed gibbons, Hylobates lar?” Animal Behaviour, vol. 82, no. 4, Oct. 2011, p. 801+. Academic OneFile, link.galegroup.com/apps/doc/A267278771/AONE?u=nysl_we_caniscl&sid=AONE&xid=8eec2f a9. Accessed 22 June 2018. Bartlett, Thad Q. “Intragroup and Intergroup Social Interactions in White-Handed Gibbons.” International Journal of Primatology, vol. 24, no. 2, Apr. 2003, p. 239. Academic Search Premier. Accessed 23 June 2018. Bartlett, Thad Q., et al. “Long-term home range use in white-handed gibbons (Hylobates lar) in Khao Yai National Park, Thailand.” American Journal of Primatology, vol. 78, no. 2, Feb. 2016, pp. 192-203. Academic OneFile, link.galegroup.com/apps/doc/A446177754/AONE?u=nysl_we_caniscl&sid=AONE&xid=fed17a 12. Accessed 23 June 2018. Beaman, Barbara A., et al. “Sterile pyuria in a population of wild white-handed gibbons (Hylobates lar).” American Journal of Primatology, vol. 71, no. 10, Oct. 2009, pp. 880-83. Academic OneFile, link.galegroup.com/apps/doc/A208121930/AONE?u=nysl_we_caniscl&sid=AONE&xid=8b13b 1cc. Accessed 23 June 2018. Brockelman, W.Y. “Inheritance and selective effects of color phase in white-handed gibbons (Hylobates lar) in central Thailand.” Mammalian Biology, vol. 69, no. 2, Feb. 2004, p. 73+. Academic OneFile, link.galegroup.com/apps/doc/A195717846/AONE?u=nysl_we_caniscl&sid=AONE&xid=c8fa8a f1. Accessed 23 June 2018. Chang, Ni-Chen, et al. “Effects of Dietary Fiber on Gut Retention Time in Captive Macaca cyclopis, Macaca fascicularis, Hylobates lar, and Pongo pygmaeus and the Germination of Ingested Seeds.” International Journal of Primatology, vol. 37, no. 6, Dec. 2016, p. 671+. Academic OneFile, link.galegroup.com/apps/doc/A474052299/AONE?u=nysl_we_caniscl&sid=AONE&xid=8c5c9 bd3. Accessed 23 June 2018. Chang, Young-Hui, et al. “External Forces and Torques Generated by the Brachiating White-Handed Gibbon (Hylobates lar).” American Journal of Physical Anthropology, vol. 113, no. 2, Oct. 2001, p. 201. Academic OneFile, link.galegroup.com/apps/doc/A72329184/AONE?u=nysl_we_caniscl&sid=AONE&xid=363471 f5. Accessed 22 June 2018. Clarke, E.A., et al. “THE VOCAL BEHAVIOUR OF FREE-RANGING WHITE- HANDED GIBBONS (HYLOBA TES LAR) IN KHAO YAI NATIONAL PARK, THAILAND.” International Journal of Primatology, vol. 27, Feb. 2006, pp. 361-62. Academic Search Premier. Accessed 23 June 2018. Clarke, Esther, et al. “The anti-predator behaviour of wild white-handed gibbons (Hylobates lar).” Behavioral Ecology and Sociobiology, vol. 66, no. 1, Jan. 2012, p. 85+. Academic OneFile, link.galegroup.com/apps/doc/A276091984/AONE?u=nysl_we_caniscl&sid=AONE&xid=557ca 946. Accessed 23 June 2018. ---. “Context-specific close-range ‘hoo’ calls in wild gibbons (Hylobates lar).” BMC Evolutionary Biology, vol. 15, no. 1, 8 Apr. 2015. Academic OneFile, link.galegroup.com/apps/doc/A459616699/AONE?u=nysl_we_caniscl&sid=AONE&xid=e6706 23c. Accessed 22 June 2018. A focus of within-group calls often called “hoo” calls that are given in several different contexts, suggesting the occurance of context-based communication in Hylobates lar. Costa, R., et al. “Assessment of environmental enrichment for different primate species under low budget: A case study.” Journal of Applied Animal Welfare Science, vol. 21, no. 2, April-June 2018, pp. 185-99. Academic Search Premier, doi:10.1080/10888705.2017.1414606. Accessed 23 June 2018. De Veer, Monique W., and Rud Van den Bos. “Assessing the quality of relationships in rehabilitating lar gibbons ( Hylobates lar).” Animal Welfare, vol. 9, no. 2, 2000, pp. 223-24. ProQuest 5000. Accessed 3 July 2018. Dirks, Wendy. “Histological reconstruction of dental development and age at death in a juvenile gibbon ( Hylobates lar ).” Journal of Human Evolution, vol. 35, nos. 4-5, Oct. 1998, p. 411+. Academic OneFile, link.galegroup.com/apps/doc/A426221937/AONE?u=nysl_we_caniscl&sid=AONE&xid=ba964 86e. Accessed 23 June 2018. Edwards, Anna-Marie A.R., and John D. Todd. “Homosexual behaviour in wild white-handed gibbons (Hylobates lar).” Primates., vol. 32, no. 2, Apr. 1991, p. 231. Academic OneFile, link.galegroup.com/apps/doc/A154228986/AONE?u=nysl_we_caniscl&sid=AONE&xid=dcb22 11f. Accessed 22 June 2018. This study found that homosexual behavior was found between two wild gibbons, an adult male and an adolescent male in the same group. Researchers suggested that this behavior was one of reassurance for the younger male, though they pointed out that this behavior is rare in general. Esser, Aristide H., et al. “Social behavior adaptations of gibbon (Hylobates lar) in a controlled environment.” Primates, vol. 20, no. 1, Jan. 1979, p. 95. Academic OneFile, link.galegroup.com/apps/doc/A154228743/AONE?u=nysl_we_caniscl&sid=AONE&xid=6fa9ad 18. Accessed 22 June 2018. Fedor, Anna, et al. “Object Permanence Tests on Gibbons (Hylobatidae).” Journal of Comparative Psychology, vol. 122, no. 4, Nov. 2008, pp. 403-17. Academic Search Premier, doi:10.1037/0735-7036.122.4.403. Frisch, John E. “Sex-differences in the canines of the gibbon (Hylobates lar).” Primates, vol. 4, no. 2, June 1963, p. 1. Academic OneFile, link.galegroup.com/apps/doc/A154228161/AONE?u=nysl_we_caniscl&sid=AONE&xid=6527c 7ce. Accessed 22 June 2018. Geissmann, Thomas, and Mathias Orgeldinger. “Neonatal Weight in Gibbons (Hylobates spp.).” American Journal of Primatology, vol. 37, no. 3, 1995, pp. 179-89. Academic Search Premier. Accessed 23 June 2018. Gillespie, Thomas R., et al. “Effects of social status and stress on patterns of gastrointestinal parasitism in wild white-handed gibbons (Hylobates lar).” American Journal of Physical Anthropology, vol. 150, no. 4, Apr. 2013, p. 602+. Academic OneFile, link.galegroup.com/apps/doc/A374767245/AONE?u=nysl_we_caniscl&sid=AONE&xid=99bb7 33e. Accessed 23 June 2018. Grueter, Cyril C., et al. “Are Hylobates lar Extripated from China?” International Journal of Primatology, vol. 30, no. 4, Aug. 2009. Academic OneFile, link.galegroup.com/apps/doc/A232944361/AONE?u=nysl_we_caniscl&sid=AONE&xid=cb33c 047. A 2009 study of the Nangunhe Nature Reserve in China, which was known to be the last stronghold of Hylobates lar in China. Researchers found there to be no auditory or visual evidence of their presence in the reserve, thereby theorizing that the gibbons have gone extinct in China. Guaterlli-Steinberg, Debbie. “Linear Enamel Hypoplasia in Gibbons.” American Journal of Physical Anthropology, vol. 112, no. 3, July 2000, p. 395+. Academic OneFile, link.galegroup.com/apps/doc/A63805428/AONE?u=nysl_we_caniscl&sid=AONE&xid=4df215f 8. The study focused on linear enamel hypoplasia, a dental indicator of stress. The study found that gibbons differ in LEH from monkeys, but not from the great apes also studied. Hyatt, Charles W. “Responses of gibbons (Hylobates lar) to their mirror images.” American Journal of Primatology, vol. 45, no. 3, July 1998, pp. 307-11. Academic Search Premier. Accessed 23 June 2018. Inoue, Yoichi, et al. “Use of experimenter-given directional cues by a young white-handed gibbon (Hylobates lar).” Japanese Psychological Research, vol. 46, no. 3, Sept. 2004, pp. 262-67. Academic Search Premier, doi:10.1111/j.1468-5584.2004.00258.x. Accessed 23 June 2018. “Interactions Between Lar Gibbons and Pig-Tailed Macaques at Fruit Sources.” American Journal of Primatology, vol. 26, no. 1, 1992, pp. 61-64. Academic Search Premier. Jildmalm, Ronald, et al. “Food Preferences and Nutrient Composition in Captive White-handed Gibbons, Hylobates lar.” International Journal of Primatology, vol. 29, no. 6, Dec. 2008, p. 1535+. Academic OneFile, link.galegroup.com/apps/doc/A232944267/AONE?u=nysl_we_caniscl&sid=AONE&xid=669ae d38. Accessed 22 June 2018. Koda, Hiroki, et al. “Soprano singing in gibbons.” American Journal of Physical Anthropology, vol. 149, no. 3, Nov. 2012, pp. 347-55. Academic Search Premier, doi:10.1002/ajpa.22124. Accessed 23 June 2018. Liebal, Katja, and Juliane Kaminski. “Gibbons ( Hylobates pileatus, H. moloch, H. lar, Symphalangus syndactylus) follow human gaze, but do not take the visual perspective of others.” Animal Cognition, vol. 15, no. 6, Nov. 2012, pp. 1211-16. Academic Search Premier, doi:10.1007/s10071-012-0543-5. Accessed 23 June 2018. Matsudaira, Kazunari, et al. “Molecular evidence for the introgression between Hylobates lar and H. pileatus in the wild.” Primates, vol. 54, no. 1, Jan. 2013, pp. 33-37. ProQuest 5000, DOI:10.1007/s10329-012-0323-5. Accessed 29 June 2018. McConkey, Kim R., et al. “Effectiveness of primate seed dispersers for an ‘oversized’ fruit, Garcinia benthamii.” Ecology, vol. 96, no. 10, Oct. 2015, pp. 2737-47. Academic Search Premier, doi:10.1890/14-1931.1.sm. Accessed 23 June 2018. Mohd Rameli, Nurul Iza Adrina, et al. “Preliminary study of activity budget, visitors’ effect and space preferred by a lar gibbon (Hylobates lar) in captivity.” Malayan Nature Journal, vol. 69, no. 4, Dec. 2017, pp. 315-21. Academic Search Premier, web.a.ebscohost.com.ezproxy.canisius.edu/ehost/detail/detail?vid=0&sid=3c8cb48a-f9d8-4f95- 94a1- 22277cc23947%40sessionmgr4008&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#AN=12712 2208&db=aph. Accessed 23 June 2018. Nettelbeck, Anouchka Rebekka. “Encounters between Lar Gibbons (Hylobates lar) and Binturongs (Arctictis binturong).” Folia Primatologica, vol. 69, no. 6, 1998, pp. 392-96. Academic Search Premier, doi:10.1159/000021659. Accessed 23 June 2018. Oka, Kenji, et al. “Brief communication: three-dimensional motion analysis of hindlimb during brachiation in a white-handed gibbon (Hylobates lar).” American Journal of Physical Anthropology, vol. 142, no. 4, Aug. 2010, p. 650+. Academic OneFile, link.galegroup.com/apps/doc/A233049908/AONE?u=nysl_we_caniscl&sid=AONE&xid=b4c37 80d. Accessed 23 June 2018. Osterberg, Petra, et al. “Gibbon (Hylobates lar) reintroduction success in Phuket, Thailand, and its conservation benefits.” American Journal of Primatology, vol. 77, no. 5, May 2015, pp. 492-501. Academic OneFile, link.galegroup.com/apps/doc/A413130769/AONE?u=nysl_we_caniscl&sid=AONE&xid=9ed60 4b1. Accessed 23 June 2018. Palombit, Ryne A. “Lethal Territorial Aggression in a White-Handed Gibbon.” American Journal of Psychology, vol. 31, no. 4, 1993, pp. 311-18. Academic Search Premier. Accessed 23 June 2018. ---. “Longitudinal patterns of reproduction in wild female siamang (Hylobates syndactylus) and...” International Journal of Primatology, vol. 16, no. 5, Oct. 1995, p. 739. Academic Search Premier. Accessed 23 June 2018. Palombit, Ryne Arthur. “Pair bonds and monogamy in wild siamang ( Hylobates syndactylus) and white-handed gibbon ( Hylobates lar) in Northern Sumatra.” Proquest Information & Learning, vol. 54, nos. 6-B, 1 Jan. 1993, p. 2942. ProQuest 5000, ezproxy.canisius.edu/login?url=https://search-proquest- com.ezproxy.canisius.edu/docview/618947068?accountid=26533. Accessed 29 June 2018. Phiphatsuwannachai, Suchada, et al. “Inter-group variability in seed dispersal by white-handed gibbons in mosaic forest.” Biotropica, vol. 50, no. 1, Jan. 2018, p. 106+. Academic OneFile, link.galegroup.com/apps/doc/A522793972/AONE?u=nysl_we_caniscl&sid=AONE&xid=93077 b59. Accessed 23 June 2018. Raemaekers, Jeremy J., and Patricia M. Raemaekers. “The Ooaa Duet of the Gibbon (Hylobates lar).” Folia Primatologica, vol. 42, nos. 3-4, 1984, pp. 209-15. Academic Search Premier, doi:10.1159/000156164. Accessed 23 June 2018. Reichard, U.H. “FEMALE LIFE HISTORIES AND REPRODUCTIVE STRATEGIES OF WILD GIBBONS (HYLOBATES LAR).” International Journal of Primatology, vol. 27, Feb. 2006, pp. 280-81. Academic Search Premier. Accessed 23 June 2018. Reichard, Ulrich. “Sleeping sites, sleeping places, and presleep behavior of gibbons (Hylobates lar ).” American Journal of Primatology, vol. 46, no. 1, Sept. 1998, pp. 35-62. Academic Search Premier. Accessed 23 June 2018. Reichard, Ulrich, and Volker Sommer. “Grooming site preferences in wild white-handed gibbons (Hylobates lar).” Primates, vol. 35, no. 3, July 1994, p. 369. Academic OneFile, link.galegroup.com/apps/doc/A154229901/AONE?u=nysl_we_caniscl&sid=AONE&xid=abf794 3f. Accessed 23 June 2018. Reichard, Ulrich H., and Claudia Barelli. “Life History and Reproductive Strategies of Khao Yai Hylobates lar: Implications for Social Evolution in Apes.” International Journal of Primatology, vol. 29, no. 4, Aug. 2008, pp. 823-84. Academic Search Premier, doi:10.1007/s10764-008-9285- 2. Accessed 23 June 2018. Savini, Tommaso, et al. “Home-range characteristics and the influence of seasonality on female reproduction in white-handed gibbons (Hylobates lar) at Khao Yai National Park, Thailand.” American Journal of Physical Anthropology, vol. 135, no. 1, Jan. 2008, p. 1+. Academic OneFile, link.galegroup.com/apps/doc/A173374280/AONE?u=nysl_we_caniscl&sid=AONE&xid=60e3a 78b. Accessed 23 June 2018. ---. “Varying Ecological Quality Influences the Probability of Polyandry in White-handed Gibbons (Hylobates lar) in Thailand.” Biotropica, vol. 41, no. 4, July 2009, p. 503+. Academic OneFile, link.galegroup.com/apps/doc/A202579934/AONE?u=nysl_we_caniscl&sid=AONE&xid=7c942 5ef. Accessed 23 June 2018. Schessler, Teryl, and Leanne T. Nash. “Food sharing among captive gibbons.” Primates., vol. 18, no. 3, July 1977, p. 677. Academic OneFile, link.galegroup.com/apps/doc/A154230103/AONE?u=nysl_we_caniscl&sid=AONE&xid=98598 87b. Accessed 22 June 2018. In a specific group of captive gibbons, food sharing was common, with younger gibbons often employing begging gestures towards older siblings or adults. Suwanvecho, Udomlux, and Warren Y. Brockelman. “Interspecific territoriality in gibbons (Hylobates lar and H. pileatus) and its effects on the dynamics of interspecies contact zones.” Primates, vol. 53, no. 1, Jan. 2012, p. 97+. Academic OneFile, link.galegroup.com/apps/doc/A276436248/AONE?u=nysl_we_caniscl&sid=AONE&xid=1d231 890. Accessed 23 June 2018. Suwanvecho, Udomlux, et al. “High interannual variation in the diet of a tropical forest frugivore (Hylobates lar).” Biotropica, vol. 50, no. 2, Mar. 2018, p. 346+. Academic OneFile, link.galegroup.com/apps/doc/A530349157/AONE?u=nysl_we_caniscl&sid=AONE&xid=cda5f4 e6. Accessed 23 June 2018. Tenaza, Richard. “Songs of Hybrid Gibbons (Hylobates lar x H. muelleri).” American Journal of Primatology, vol. 8, no. 3, 1985, pp. 249-53. Academic Search Premier. Accessed 23 June 2018. Terleph, Thomas A., et al. “Lar gibbon (Hylobates lar) great call reveals individual caller identity.” American Journal of Primatology, vol. 77, no. 7, July 2015, pp. 811-21. Academic OneFile. ---. “Age related decline in female lar gibbon great call performance suggests that call features correlate with physical condition.” BMC Evolutionary Biology, vol. 16, 5 Jan. 2016, pp. 1-13. Academic Search Premier, doi:10.1186/s12862-015-0578-8. Accessed 23 June 2018. Vereecke, E., et al. “The bipedal locomotion of Hylobates lar: preliminary results.” American Journal of Physical Anthropology, 2003, p. 215. Academic OneFile, link.galegroup.com/apps/doc/A99119596/AONE?u=nysl_we_caniscl&sid=AONE&xid=a0770d 5b. Accessed 22 June 2018. Preliminary results of this study showed that gibbons are the most bipedal of the non-human primates. The study looked into the positioning of the feet, legs, and hips of the gibbons while observing the motion itself. Vereecke, Evie E., et al. “Locomotor versatility in the white-handed gibbon (Hylobates lar): A spatiotemporal analysis of the bipedal, tripedal, and quadrupedal gaits.” Journal of Human Evolution, vol. 50, no. 5, May 2006, p. 552+. Academic OneFile, link.galegroup.com/apps/doc/A194202075/AONE?u=nysl_we_caniscl&sid=AONE&xid=8552b 6c7. Accessed 22 June 2018. Giorgi, A., Montebovi, G., & Alleva, E., (2018). A behavioural case study of early social isolation of a subadult white-handed gibbon (Hylobates lar). Folia Primatol, 89:287-294. DOI: 10.1159/000487926.

Fischer, J.O., & Geissmann, T., (1990). Group harmony in gibbons: Comparison between white-handed gibbon (Hylobates lar) and siamang (H. syndactylus). Primates, 31.4:481-494. DOI: 10.1007/BF02382532

Geissmann, T., (2009). Door slamming: Tool-use by a captive white-handed gibbon (Hylobates lar). Gibbon Journal, 5.

Jildmalm, R., Amundin, M., & Laska, M., (2008). Food preferences and nutrient composition in captive white-handed gibbons, Hylobates lar. International Journal of Primatology, 29.6:1535-1547. DOI: 10.1007/s10764-008-9314-1

Liebal, K., & Kaminski, J., (2012). Gibbons (Hylobates pileatus, H. moloch, H. lar, Symphalangus syndactylus) follow human gaze, but do not take the visual perspective of others. Animal Cognition, 15.6: 1211-1216. DOI: 10.1007/s10071-012-0543-5

Palombit, R.A., (1995). Longitudinal patterns of reproduction in wild female siamang (Hylobates syndactylus) and white-handed gibbons (Hylobates lar). International Journal of Primatology, 16.5:739-760. DOI: 10.1007/BF02735718

Schessler, T., & Nash, L.T., (1977). Food sharing among captive gibbons (Hylobates lar). Primates, 18.3:677-689. DOI: 10.1007/BF02383142

Shepherdson, D., Bemment, N., Carman, M, & Reynolds, S., (1989). Auditory enrichment for Lar gibbons Hylobates lar at London Zoo. International Zoo Yearbook, 28.1. DOI: 10.1111/j.1748- 1090.1989.tb03294.x

Cooke, C.M., & Schillaci, M.A., (2007). Behavioral responses to the zoo environment by white handed gibbons. Applied Animal Behaviour Science, 106.1-3:125-133. DOI: 10.1016/j.applanim.2006.06.016

Olson, D.A., Ellis, J.E., & Nadler, R.D., (1990). Hand preferences in captive gorillas, orang-utans and gibbons. American Journal of Primatology, 20.2. DOI: 10.1002/ajp.1350200203