1. QPS Netherlands B.V. 9713 GZ Groningen, The Netherlands
2. PRA International, 9471 GP Zuidlaren, The Netherlands
3. Lentis Mental Health Organisation, 9725 AG Groningen, The Netherlands
4. Rob Giel Onderzoekscentrum, Department of Psychiatry, University Medical Centre Groningen, University of Groningen, 9700 RB Groningen, The Netherlands