Não informado. (1972). Annals of the Research Institute of Epidemiology and Microbiology. Ministery of Public Health.
Chicago-viite (17. p.)Não informado. Annals of the Research Institute of Epidemiology and Microbiology. Sofia: Ministery of Public Health, 1972.
MLA-viite (8. p.)Não informado. Annals of the Research Institute of Epidemiology and Microbiology. Ministery of Public Health, 1972.
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