"Smallpox". Armed Forces Institute of Pathology: Department of Infectious and Parasitic Diseases. Arkiveret fra originalen 9. oktober 2007. Hentet 18. august 2024.
Babkin, I.V.; Babkina, I.N. (2015). "The Origin of the Variola Virus". Viruses. 7 (3): 1100-1112. doi:10.3390/v7031100.
Mühlemann, B.; et al. (2020). "Diverse variola virus (smallpox) strains were widespread in northern Europe in the Viking Age". Science. 369 (6502). doi:10.1126/science.aaw8977.
Nelson MC, Rogers J (1992). "The Right to Die? Anti-vaccination Activity and the 1874 Smallpox Epidemic in Stockholm". Social History of Medicine. 5 (3): 369-388. doi:10.1093/shm/5.3.369.
"Smallpox". Armed Forces Institute of Pathology: Department of Infectious and Parasitic Diseases. Arkiveret fra originalen 9. oktober 2007. Hentet 18. august 2024.