1. Fields BN, Knipe DM, Howley PM. Fields virology. 5th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2007.
2. Fenner F. Smallpox and its eradication. Geneva: World Health Organization; 1988.
3. Cyrklaff M, Risco C, Fernandez JJ, et al. Cryo-electron tomography of vaccinia virus. Proc Natl Acad Sci U S A. 2005;102:2772–7.
4. Mandell GL, Bennett JE, Dolin R. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. 7th ed. Philadelphia: Churchill Livingstone/Elsevier; 2010.
5. Goebel SJ, Johnson GP, Perkus ME, Davis SW, Winslow JP, Paoletti E. The complete DNA sequence of vaccinia virus. Virology. 1990;179:247–66, p. 517–63.