Rattanaporn Burimsittichai และ Somrat Charuluxananan. (2014) Comparison of intravenous tramadol and ketamine for prevention of catheter-related bladder discomfort after laparoscopic surgery: A randomized, placebo-controlled, double-blind study. Chulalongkorn University:ม.ป.ท.Rattanaporn Burimsittichai และ Somrat Charuluxananan. 2014. Comparison of intravenous tramadol and ketamine for prevention of catheter-related bladder discomfort after laparoscopic surgery: A randomized, placebo-controlled, double-blind study. ม.ป.ท.:Chulalongkorn University;Rattanaporn Burimsittichai และ Somrat Charuluxananan. Comparison of intravenous tramadol and ketamine for prevention of catheter-related bladder discomfort after laparoscopic surgery: A randomized, placebo-controlled, double-blind study. ม.ป.ท.:Chulalongkorn University, 2014. Print.