1. Results from the 2004 National Survey on Drug Use and Health: national findings,2005
2. The state of the drugs problem in Europe: annual report 2005,2005
3. Cannabis: a health perspective and research agenda,1997
4. Alcohol and drug use in UK university students;Webb;Lancet,1996
5. Cannabis use and dependence in a New Zealand birth cohort;Fergusson;N Z Med J,2000