1. McCaig LF. National Hospital Ambulatory Medical Care Survey: 1998 Emergency Department Summary. Advance data from vital and health statistics; No. 313. Hyattsville, MD: National Center for Health Statistics; 2000; 9
2. Managing pain;Merboth;Nurs Clin North Am,2000
3. Clinicians are encouraged to use HIV patients' pain as a fifth vital sign;Kutzen;HIV Clin,2000
4. “Who's taking your 5th vital sign?”;Flaherty;J Gerontol A Biol Sci Med Sci,2001
5. Pain as the fifth vital sign. J Am Optom Assoc 1999;70:619–20