[EPIDEMIOLOGICAL STUDIES ON PERTUSSIS AND PARAPERTUSSIS].
D002031:Bulgaria; D016021:Epidemiologic Studies; D004813:Epidemiology; D006801:Humans; D010567:Pertussis Vaccine; D014917:Whooping Cough
D010567:Pertussis Vaccine
BULGARIA; EPIDEMIOLOGY; PERTUSSIS VACCINE; WHOOPING COUGH