1. American Psychiatric Association (1994) Diagnostic and Statistical Manual of Mental Disorders, 4th edn (DSM IV). Washington, DC: APA.
2. Mayfield, D., McLeod, G. and Hall, M. S. W. (1974) "The CAGE Questionnaire: Validation of a New Alcoholism Screening Instrument'. American Journal of Psychiatry 131: 1121-3.
3. Singleton, N., Meltzer, H., Gatward, R. et al. (1998) Psychiatric Morbidity among Prisoners in England and Wales. London: Office for National Statistics.