Hang, L, D Shao, and W Sun. “The ED50and ED95 of Ketamine for Prevention of Postoperative Hyperalgesia After Remifentanil-Based Anaesthesia in Patients Undergoing Laparoscopic Cholecystectomy”. Swiss Medical Weekly 141, no. 1920 (May 9, 2011): w13195. Accessed June 17, 2024. https://smw.ch/index.php/smw/article/view/1284.