Li, Y., Carroll, D. S., Gardner, S. N., Walsh, M. C., Vitalis, E. A., & Damon, I. K. (2007). On the origin of smallpox: Correlating variola phylogenics with historical smallpox records. National Academy of Sciences.

Li, Yu, Darin S. Carroll, Shea N. Gardner, Matthew C. Walsh, Elizabeth A. Vitalis, ja 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.