Nathanson N, Martin J (1979). "The epidemiology of poliomyelitis: enigmas surrounding its appearance, epidemicity, and disappearance". Am J Epidemiol. 110 (6): 672–92. doi:10.1093/oxfordjournals.aje.a112848. PMID400274.
Nathanson N, Martin J (1979). "The epidemiology of poliomyelitis: enigmas surrounding its appearance, epidemicity, and disappearance". Am J Epidemiol. 110 (6): 672–92. doi:10.1093/oxfordjournals.aje.a112848. PMID400274.