Endoscopic extraction of a gastric submucosal foreign body after precise location with endoscopic ultrasound combined with endoscopic submucosal dissection - Mao, Yuqing; Hu, Bin; Gong, Xiaoyuan; Luo, Shengzheng; Xia, Youchen; Fu, Chenghong; Li, Baiwen (Endoscopy, 2021)