[On some problems in the use of viral vaccines in Bulgaria].
D002031:Bulgaria; D006306:Health Surveys; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D012882:Skin Tests; D012899:Smallpox / Q000276:immunology*; D012900:Smallpox Vaccine; D014611:Vaccination
D012900:Smallpox Vaccine
Uber einige Probleme der Anwendung von Virusimpfstoffen in Bulgarien.