Não informado. (1972). Annals of the Research Institute of Epidemiology and Microbiology. Ministery of Public Health.
Chicago-Zitierstil (17. Ausg.)Não informado. Annals of the Research Institute of Epidemiology and Microbiology. Sofia: Ministery of Public Health, 1972.
MLA-Zitierstil (8. Ausg.)Não informado. Annals of the Research Institute of Epidemiology and Microbiology. Ministery of Public Health, 1972.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.