Jie-hui Tan, et al. “Viral Hepatitis B and C Infections Increase the Risks of Intrahepatic and Extrahepatic Cholangiocarcinoma: Evidence from a Systematic Review and Meta-Analysis”. Turkish Journal of Gastroenterology, vol. 31, no. 3, Apr. 2020, pp. 246-5, https://tjg.avesjournals.com/index.php/tjg/article/view/3871.