OKAN, A. (1998) “Frequency of HBsAg/anti-HCV seropositivity and its relationship with risk factors in extrahepatic malignancies”, Turkish Journal of Gastroenterology, 9(1), pp. 28–31. Available at: https://turkjgastroenterol.org/index.php/tjg/article/view/850 (Accessed: 1 January 2026).