Respiratory infection--Pennsylvania. 1977.
D004196:Disease Outbreaks; D049673:History, 20th Century; D006801:Humans; D007877:Legionnaires' Disease / Q000266:history*; D015143:Philadelphia / Q000453:epidemiology; D011014:Pneumonia / Q000453:epidemiology / Q000266:history; D012140:Respiratory Tract Diseases / Q000453:epidemiology / Q000266:history*