1. Klinikum rechts der Isar, Technical University Munich; Institute of General Practice; Orleansstrasse 47 München Germany 81667
2. University of Torino; Women's Headache Center and Service for Acupuncture in Gynecology and Obstetrics, Department of Surgical Sciences; Via Ventimiglia 3 Torino Italy 10126
3. Charité - Universitätsmedizin Berlin; Institute for Social Medicine, Epidemiology and Health Economics; Luisenstrasse 57 Berlin Germany 10117
4. Beijing University of Chinese Medicine; Centre for Evidence-Based Chinese Medicine; 11 Bei San Huan Dong Lu, Chaoyang District Beijing China 100029
5. Memorial Sloan-Kettering Cancer Center; Department of Epidemiology and Biostatistics; New York USA
6. Plymouth University Peninsula Schools of Medicine and Dentistry; Primary Care; 25 Room N32, ITTC Building Tamar Science Park Plymouth UK PL6 8BX