1. 1B.P. Allen (1994 )Personality Theorists. Allyn and Bacon, Needham Heights, Massachusetts.
2. 2R.J. Campbell (1996 )Psychiatric Dictionary, 7th edn. Oxford University Press, Oxford, New York.
3. 3P.L. Chinn, and M.K. Kramer (1995 )Theory and Nursing: a systematic approach, 3rd edn. Mosby Year Book, St Louis, Missouri.
4. Subjectivity of pain
5. The meaning of pain management