Two-stage treatment with preoperative endoscopic retrograde cholangiopancreatography (ERCP) compared with single-stage treatment with intraoperative ERCP for patients with symptomatic cholelithiasis with possible choledocholithiasis - Rábago, L R; Vicente, C; Soler, F; Delgado, M; Moral, I; Guerra, I; Castro, J L; Quintanilla, E; Romeo, J; Llorente, R; Vázquez Echarri, J; Martínez-Veiga, J L; Gea, F (Endoscopy, 2006)