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(2010-04-21). Evolutionary Worlds without End. : Oxford University Press. Retrieved 22 May. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199544950.001.0001/acprof-9780199544950.
Evolutionary Worlds without End. : Oxford University Press, 2010-04-21. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199544950.001.0001/acprof-9780199544950.
Plotkin H. Evolutionary Worlds without End. Oxford University Press; 2010. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199544950.001.0001/acprof-9780199544950. Accessed May 22, 2013.