YILMAZ, Uğur, et al. “THE SUBCUTANEOUS EMPHYSEMA AND RETROPERITONEAL PERFORATION CAUSED BY ENDOSCOPIC SPHINCTEROTOMY”. Turkish Journal of Gastroenterology, vol. 4, no. 1, Jan. 1993, pp. 246-8, https://turkjgastroenterol.org/index.php/tjg/article/view/214.