1. Addiction Switzerland Research Institute; Lausanne Switzerland
2. Faculty of Social and Behavioural Sciences; Utrecht University; Utrecht the Netherlands
3. Institute for Social Science Research; The University of Queensland; Brisbane Australia
4. University College London; London UK
5. Global Drug Survey Ltd.; London UK
6. Behavioural Science Institute; Radboud University; Nijmegen the Netherlands
7. Institute of Psychology; Eötvös Loránd University; Budapest Hungary