1. Federal Institute for Vocational Education and Training (BIBB), 53113 Bonn, Germany
2. Research Centre for Education and the Labour Market (ROA), Maastricht University, 6200 MD Maastricht, The Netherlands
3. Department of Spatial and Environmental Planning, University of Kaiserslautern-Landau (RPTU), 67663 Kaiserslautern, Germany
4. Department of Sociology, University of Tuebingen, 72074 Tübingen, Germany