Appropriateness and Diagnostic Yield of Upper Gastrointestinal Endoscopy in an Open-Access Endoscopy Unit. - Gonvers,J.J.; Burnand,B.; Froehlich,F.; Pache,I.; Thorens,J.; Fried,M.; Kosecoff,J.; Vader,J.P.; Brook,R.H. (Endoscopy, 1996)