1. Forest. (2004). In The Columbia Encyclopedia (6th ed.). New York: Columbia University Press. Retrieved October 15, 2007, from Questia.com
2. Animal. (2004). In The Columbia Encyclopedia (6th ed.). New York: Columbia University Press. Retrieved October 15, 2007, from Questia.com
3. Ibid.
4. Biological Diversity. (2004). In The Columbia Encyclopedia (6th ed.). New York: Columbia University Press. Retrieved October 15, 2007, from Questia.com
5. Ibid.
6. Tropical Forest. (2007). In Encyclopedia Britannica. Retrieved October 15, 2007, from Encyclopedia Britannica Online: http://www.britannica.com/eb/article-70770