Medicine in the USA: historical vignettes. XXI. Medical practice: specialization.
D000329:Advertising / Q000266:history; D000574:American Medical Association / Q000266:history; D003253:Consultants; D006666:History of Medicine; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D013677:Medical Laboratory Science / Q000266:history; D012017:Referral and Consultation; D012955:Societies, Medical / Q000266:history; D013038:Specialization / Q000266:history*; D014481:United States