1. Leiden University Medical Center; Department of Dermatology; PO Box 9600 B1-Q Leiden Netherlands 2300 RC
2. Cochrane; Bahrain Branch; Box 25438 Awali Bahrain
3. King's College London; Institute of Psychiatry, Psychology & Neuroscience; Biostatistics and Health Informatics; Denmark Hill London UK
4. Academic Medical Center; Department of Dermatology; P.O. Box 22660 Amsterdam Netherlands 1100 DD
5. The University of Nottingham; c/o Cochrane Skin Group; Nottingham UK