Curry, Erin, Sina Safayi, Randi Meyerson, and Terri Roth. “Reproductive Trends of Captive Polar Bears in North American Zoos: A Historical Analysis”. Journal of Zoo and Aquarium Research 3, no. 3 (July 23, 2015): 99–106. Accessed March 29, 2024. https://www.jzar.org/jzar/article/view/133.