Sabatowski R, Huber M, Meuser T, Radbruch L
Pain Clinic, Department of Anaesthesiology and Intensive Care, Department of Psychosomatic and Psychotherapy, University of Cologne, 59024 Cologne, Germany.
Cephalalgia. 2001 Mar;21(2):154-6. doi: 10.1046/j.1468-2982.2001.00180.x.