1. Department of Psychiatry, Cambridge Public Health, Herchel Smith Building, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SZ, UK
2. Department of Public Health and Clinical Medicine, Umeå University, SE-901 87 Umeå, Sweden
3. Innlandet Hospital Trust, 2312 Ottestad, Norway
4. Center for Research on Extremism, University of Oslo, 0317 Oslo, Norway
5. St George’s Medical School, University of London, London SW17 0RE, UK
6. School of Clinical Medicine, University of Cambridge Medical Library, Cambridge CB2 0SP, UK