Does Inappropriate use explain geographic variations in the use of Health Care Services? A study of three procedures. - Chassin,M.R.; Kosecoff,J.; Park,R.E.; Winslow,C.M.; Kahn,K.L.; Merrick,N.J.; Keesey,J.; Fink,A.; Solomon,D.H.; Brook,R.H. (JAMA, 1987)