1. Adler, P. (1985) Wheeling and Dealing: An Ethnography of an Upper-Level Drug Dealing and Smuggling Community. New York: Columbia University Press.
2. Agar, M. (1973) Ripping and Running: a Formal Ethnography of Urban Heroin Addicts. New York: Seminar Press.
3. Ajzen, I. (1988) Attitudes, Personality, and Behaviour. Chicago: Dorsey Press.
4. Ajzen, I. and Fishbein, M. (1980) Understanding Attitudes and Predicting Social Behaviour. Englewood Cliffs, NJ: Prentice Hall.
5. The theory of planned behavior