Efficacy of Underwater Endoscopic Mucosal Resection for Superficial Non-Ampullary Duodenal Epithelial Tumor oleh Masanori Furukawa, Akira Mitoro, Takahiro Ozutumi, Yukihisa Fujinaga, Keisuke Nakanishi, Koh Kitagawa, Soichiro Saikawa, Sinya Sato, Yasuhiko Sawada, Hiroaki Takaya, Kosuke Kaji, Hideto Kawaratani, Tadashi Namisaki, Kei Moriya, Takemi Akahane, Junichi Yamao, Hitoshi Yoshiji