[Some properties of the strains of Newcastle disease virus isolated in Bulgaria. V. Pathogenicity to chick embryos].
D000818:Animals; D002031:Bulgaria; D002642:Chick Embryo; D009522:Newcastle disease virus / Q000302:isolation & purification / Q000472:pathogenicity*
Prouchvaniia vurkhu niakoi svoistva na shtamove na virusa na psevdochumata po ptitsite, izolirani u nas. V. Patogennost za kokoshi embrioni