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McCrystal, P., Percy, A., & Higgins, K (2007). Exclusion and Marginalisation: The Experience of School Exclusion on Drug Use and Antisocial Behaviour. Journal of Youth Studies 10 (1).
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McCrystal, P., Percy, A., & Higgins, K (2006). Drug Use Patterns and Behaviours of Young People at an Increased Risk of Drug Abuse during Adolescence. International Journal of Drug Policy 17, 393-401
McCrystal, P., Higgins, K., & Percy, A. (2006). School Exclusion Drug Use and Delinquency in Adolescence. Journal of Adolescence 29, 829-836.
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McCrystal, P., Higgins, K., Percy, A., & Thornton, M. (2005) Adolescent Substance Abuse Among Young People Excluded from School in Belfast. Drugs: Education Policy and Prevention, 12, 101-113.
McCrystal, P., Higgins, K., Percy, A. (2005). Drug use amongst 12 and 13 year olds attending emotional and behavioral difficulty units in Belfast. Emotional and Behavioural Difficulties 10, 3, 203-218.
McCrystal, P., Higgins, K., Percy, A., & Thornton, M. (2005). Substance Abuse among 12 and 13-year old Young People in Belfast at a High Risk of Developing Problem Drug Use, Child care in Practice, 11, 3, 313-322.
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McCrystal P, Higgins, K and Percy, A (2001) Measuring Social Exclusion: A Lifespan Approach. Radical Statistics Winter 01