Ramosetron vs. ramosetron plus dexamethasone for the prevention of postoperative nausea and vomiting (PONV) after laparoscopic cholecystectomy: prospective, randomized, and double-blind study - Ryu, J H; Chang, J E; Kim, H R; Hwang, J W; Oh, A Y; Do, S H (Int J Surg, 2013)