Gel immersion endoscopic submucosal dissection for an anorectal tumor with hemorrhoids close to the dentate line - Tashima, Tomoaki; Nakano, Yuya; Jinushi, Ryuhei; Miyaguchi, Kazuya; Terada, Rie; Kawasaki, Tomonori; Ryozawa, Shomei (Endoscopy, 2021)