Cita APA

Fenner, F., & Fenner, F. (1988). Smallpox and its eradication. Geneva: World Health Organization.

Citación estilo Chicago

Fenner, F., y F. Fenner. Smallpox and Its Eradication. Geneva: World Health Organization, 1988.

Cita MLA

Fenner, F., y F. Fenner. Smallpox and Its Eradication. Geneva: World Health Organization, 1988.