PARLAK, Erkan, et al. “Is Determination of Initial Attack Severity Predictive for Long-Term Prognosis in Patients With Total Ulcerative Colitis?”. Turkish Journal of Gastroenterology, vol. 11, no. 3, Jan. 2000, pp. 231-4, https://www.turkjgastroenterol.org/index.php/tjg/article/view/1080.