Howell, Christian Paul, and Simon Childs. “Use of a ‘Creep’: Zoo Animal Management to Encourage Reproductive Behaviours in Captive Bornean Orangutans (Pongo Pygmaeus)”. Journal of Zoo and Aquarium Research 8, no. 3 (July 31, 2020): 203-207. Accessed October 29, 2020. https://jzar.org/jzar/article/view/368.