1. Department of Educational Sciences, University of Potsdam, Potsdam, Germany.
2. Institute of Education, National Anti-Bullying Research and Resource Centre, Dublin City University, Dublin, Ireland.
3. Department of Health Sciences, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany.
4. Institute for Research, Development and Evaluation, Bern University of Teacher Education, Bern, Switzerland.
5. Department of Psychology, Penn State University, University Park, Pennsylvania, USA.
6. Department of Psychology, DePaul University, Chicago, Illinois, USA.