Maffei, M, and JM Dumonceau. “Transnasal Esogastroduodenoscopy (EGD): Comparison With Conventional EGD and New Applications”. Swiss Medical Weekly 138, no. 4546 (November 15, 2008): 658–664. Accessed February 20, 2025. https://smw.ch/index.php/smw/article/view/914.