GÜR, Gürden, et al. “Hemorrhagic Colitis Due to Ampicillin-Sulbactam: A Report of Four Cases”. Turkish Journal of Gastroenterology, vol. 10, no. 3, Jan. 1999, pp. 207-10, https://www.turkjgastroenterol.org/index.php/tjg/article/view/990.