• Gould, Stephen Jay (1980). The Panda’s Thumb (1st ed.). New York: Norton.
• Lovejoy, Arthur O. (1936). The Great Chain of Being: A Study of the History of an Idea. Cambridge, Massachusetts: Harvard University Press.
• Prothero, Donald R. (2007). Evolution: What the Fossils Say and Why it Matters. Columbia University Press.
• Overview of Transitional Forms from Cal Berkeley: http://evolution.berkeley.edu/evolibrary/article/lines_03
• Fossils Show Stasis and No Transitional Forms. The Institute for Creation Research, n.d. Web. 19 June 2013.