1. Clinical practice guideline: Acute pain management: Operative or medical procedure and trauma. AHCPR Pub. No. 920032;Acute Pain Management Guideline Panel, Agency for Health Care Research and Quality,1992
2. American Medical Association (2003). Pain management: Pathophysiology of pain and pain assessment. Retrieved January 21, 2007, from http://www.ama-cmeonline.com/pain_mgmt/module01/index.htm.
3. Experimental pain stimulates respiration and attenuates morphine-induced respiratory depression: A controlled study in human volunteers;Borgbjerg;Pain,1996
4. Surgical wound pain: A trial of two treatments;Briggs;Journal of Wound Care,1996
5. Assessment of chronic pain: I. Aspects of the reliability and validity of the visual analog scale;Carlsson;Pain,1983