Fission and fusion in the field of surgery.
D004501:Education, Medical / Q000592:standards; D013502:General Surgery / Q000145:classification / Q000193:education / Q000266:history; D049672:History, 19th Century; D049673:History, 20th Century; D010414:Pennsylvania; D011787:Quality of Health Care; D012106:Research / Q000592:standards; D013038:Specialization / Q000266:history*