Henderson, D. A. "Epidemiology in the Global Eradication of Smallpox". International Journal of Epidemiology (ingilis). 1 (1). 1972-03-20: 25–30. doi:10.1093/ije/1.1.25. ISSN0300-5771. PMID4669176.
Henderson, D. A. "Epidemiology in the Global Eradication of Smallpox". International Journal of Epidemiology (ingilis). 1 (1). 1972-03-20: 25–30. doi:10.1093/ije/1.1.25. ISSN0300-5771. PMID4669176.
Henderson, D. A. "Epidemiology in the Global Eradication of Smallpox". International Journal of Epidemiology (ingilis). 1 (1). 1972-03-20: 25–30. doi:10.1093/ije/1.1.25. ISSN0300-5771. PMID4669176.