Dual-port distal pancreatectomy using a prototype endoscope and endoscopic stapler: a natural orifice transluminal endoscopic surgery (NOTES) survival study in a porcine model - Ryou, M; Fong, D G; Pai, R D; Tavakkolizadeh, A; Rattner, D W; Thompson, C C (Endoscopy, 2007)