1. Department of Orthopedagogics, Ghent University, H. Dunantlaan 2, B-9000 Ghent, Belgium.
2. Department of Orthopedagogics, Ghent University, Belgium.
3. Scottish Addiction Studies, Department of Applied Social Science, University of Stirling, Scotland
4. Therapeutic Community Emiliehoeve, Den Haag, The Netherlands.