Gel immersion endoscopic submucosal dissection using a novel gel product for a duodenal epithelial tumor - Tashima, Tomoaki; Miyaguchi, Kazuya; Terada, Rie; Mashimo, Yumi; Tanisaka, Yuki; Kawasaki, Tomonori; Ryozawa, Shomei (Endoscopy, 2021)