1. Johannes Gutenberg University Mainz, Department of Educational Science, Saarstr. 21, 55122 Mainz, Germany ().
2. University of Duisburg-Essen, Department of Sociology, Lotharstrasse 65, 47057 Duisburg, Germany ().
3. Norwegian Institute of Public Health, Department of Childhood and Families, Division of Mental and Physical Health, PO Box 222, 0213 Skøyen, Norway ().
4. Norwegian Institute of Public Health, Department of Childhood and Families, Division of Mental and Physical Health, PO Box 222, 0213 Skøyen, Norway, ().