James, Allwin, Premkumar Karunakaran, Ratnakar Kini, and Pugazhendhi Thangavel. “Patulous Upper Esophageal Sphincter - an Unusual Endoscopic Finding”. Turkish Journal of Gastroenterology 29, no. 1 (January 1, 2018): 116–118. Accessed January 1, 2026. https://turkjgastroenterol.org/index.php/tjg/article/view/3208.