Evaluation of the presence of Helicobacter species in the biliary system of Turkish patients with cholelithiasis - BOSTANOĞLU, Ebru; KARAHAN, Zeynep Ceren; BOSTANOĞLU, Akın; SAVAŞ, Berna; ERDEN, Esra; KIYAN, Mehmet (Turkish Journal of Gastroenterology, 2010)