Nossal, Gustav J. V. "Life, Death and the Immune System."
Scientific American
269.3 (1993): 52-62. Print.
Campbell, Neil A., Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson.
AP Edition Biology
. 8th ed. New York: Benjamin/Cummings, 2008. Print.