"Animals Kept in Zoos." Animal Facts. Animal Facts, n.d. Web. 08 May 2016.

Estrada, Orietta C. "10 Reasons to Skip Your Next Zoo Visit." One Green Planet. One Green Planet, 9 Dec. 2013. Web. 08 May 2016

Rose, Naomi A., PhD. "Whales, Dolphins Don't Belong in Tanks." The Humane Society of the United States. The Humane Society of the            United States, 14 Nov. 2005. Web. 8 May 2016.

"10 Facts about Zoos." Captive Animals' Protection Society. Captive Animals' Protection Society, 3 Mar. 2010. Web. 8 May 2016.

"Zoo Statistics." Static Brain. Static Brain, 8 Apr. 2015. Web. 8 May 2016.

Hutchins, Micheal, PhD, and Bridget M. Kuehn. "Is It Ethical to Keep Animals in Zoos?" American Vetrinary Medical Foundation. America          Vetrenary Medical Foundation, 15 Nov. 2002. Web. 8 May 2016.

Carlson, Bruce, and Kim McCoy. "Should Big Animals Live in Aquariums?" Scuba Diving. Scuba Diving, 19 May 2010. Web. 8 May 2016.