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Li, Yu, Darin S. Carroll, Shea N. Gardner, Matthew C. Walsh, Elizabeth A. Vitalis, e Inger K. Damon. On the Origin of Smallpox: Correlating Variola Phylogenics With Historical Smallpox Records. National Academy of Sciences, 2007.

Li, Yu, et al. On the Origin of Smallpox: Correlating Variola Phylogenics With Historical Smallpox Records. National Academy of Sciences, 2007.