Jin-Kyu Cho, et al. “Simultaneous Osteosarcoma and Adenocarcinoma of the Gallbladder: A Rare Case Report and Literature Review”. Turkish Journal of Gastroenterology, vol. 30, no. 6, July 2019, pp. 569-72, https://tjg.avesjournals.com/index.php/tjg/article/view/3725.