The improtance of the sphincterotomy in the diagnosis of periampullary carcinoma: analysis of 664 patients who underwent ERCP - BAYRAKTAR, Yusuf; ÖZGENÇ, Ahmet; ÖZDEMİR, Arif and ÖKSÜZOĞLU, Gürol and ARSLAN, Serap and COŞKUN, Teoman and UZUNALİMOĞLU, Bedri (Turkish Journal of Gastroenterology, 1997)