Allwin James, Premkumar Karunakaran, Ratnakar Kini, and Pugazhendhi Thangavel. 2019. “Patulous Upper Esophageal Sphincter - an Unusual Endoscopic Finding”. Turkish Journal of Gastroenterology 29 (1):116-18. https://tjg.avesjournals.com/index.php/tjg/article/view/3496.