A randomized double-blind controlled study comparing epidural morphine and epidural morphine with ketamine for post-op pain relief in abdominal surgeries / 
Yogi dela Cruz-Lazaga [and two others] 
<br/><br/>St. Luke's J Medicine, 2005 3 (2) pages 24-30 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Morphine<br/>Anesthesia, Epidural<br/>Ketamine<br/>Pain, Postoperative