Analysis of risk factors affecting the development of peptic ulcer perforation: case-control study - Akbulut, Sami; Caliskan, Ali; Saritas, Hasan; Demyati, Khaled; Bilgic, Yilmaz; Unsal, Selver; Koc, Cemalettin; Yilmaz, Sezai (Gastroenterology Review/Przegląd Gastroenterologiczny, 2021)