Enlace original:
https://apps.who.int/iris/handle/10665/68313
Fenner, Frank
,
Breman, Joel G
,
World Health Organization
,
[Report on a visit to the People's Republic of China to consider matters relating to the certification of smallpox eradication, 14-30 July 1979 / F. Fenner and J.G. Breman]