Over-The-Scope Clips (OTSC©) Versus Surgery for Refractory Peptic Ulcer Bleeding - Kuellmer, A; Mangold, T; Bettinger, D; Maruschke, L; Wannhoff, A; Caca, K; Wedi, E; Jung, C; Kleemann, T; Schulz, T; Thimme, R; Schmidt, A (Endoscopy, 2021)