Henderson, D. A. (20 Mar 1972). "Epidemiology in the Global Eradication of Smallpox". International Journal of Epidemiology (بالإنجليزية). 1 (1): 25–30. DOI:10.1093/ije/1.1.25. ISSN:0300-5771. PMID:4669176.
Henderson, D. A. (20 Mar 1972). "Epidemiology in the Global Eradication of Smallpox". International Journal of Epidemiology (بالإنجليزية). 1 (1): 25–30. DOI:10.1093/ije/1.1.25. ISSN:0300-5771. PMID:4669176.
Henderson, D. A. (20 Mar 1972). "Epidemiology in the Global Eradication of Smallpox". International Journal of Epidemiology (بالإنجليزية). 1 (1): 25–30. DOI:10.1093/ije/1.1.25. ISSN:0300-5771. PMID:4669176.