1. The treatment of cancer pain;Foley;N Engl J Med,1985
2. Cancer pain relief;World Health Organization,1986
3. Cancer pain relief and palliative care;World Health Organization,1990
4. Management of cancer pain: clinical practice guideline no. 9;Jacox,1994
5. Pain and quality of life: clinical issues and implications for research;Portenoy;Oncology,1990