[Frequency, propagation, and changes in certain internal diseases in Bulgaria; data from 6 hospitals].
D002031:Bulgaria; D004813:Epidemiology; D006761:Hospitals; D006801:Humans
EPIDEMIOLOGY
Chestota, razprostranenie i promeni v protichaneto na niakoi v"treshni bolesti u nas; po danni ot 6 bolnichni zavedeniia.