TUNCER, İlyas, et al. “The Effects of Ursodeoxycholic Acid Alone and Ursodeoxycholic Acid Plus Low-Dose Acetylsalicylic Acid on Radiolucent Gallstones”. Turkish Journal of Gastroenterology, vol. 14, no. 2, Jan. 2003, pp. 91-96, https://turkjgastroenterol.org/index.php/tjg/article/view/1246.