1. Department of Special Needs Education and Youth Care, University of Groningen, Royal Kentalis, Sint-Michielsgestel, Grote Rozenstraat 38, 9712 TJ Groningen, the Netherlands
2. Department of Developmental Psychology, Radboud University, Nijmegen, the Netherlands
3. Department of Special Education, Radboud University, and retired assistant director of Royal Kentalis, Sint-Michielsgestel, the Netherlands
4. Department of Sociology, University of Groningen, Groningen, the Netherlands
5. Department of Special Needs Education and Youth Care, University of Groningen, the Netherlands