1. Pain and its treatment in outpatients with metastatic cancer;Cleeland;N Engl J Med,1994
2. Stjernsward J, Teoh N. The scope of the cancer pain problem. In: Foley KM, Bonica JJ, Ventafridda V, eds. Advances in Pain Research and Therapy, Vol. 16. 1990:7–12.
3. The effect of drug regulation on the management of cancer pain;Portenoy;NY J Med,1991
4. Barriers to the management of cancer pain;Cleeland;Oncology (suppl),1987
5. Patient-related barriers to management of cancer pain;Ward;Pain,1993