1. 3R Research Centre, Central Animal Laboratory, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
2. Centre for Equine and Animal Science, Writtle College, Chelmsford, Essex CM1 3RR, UK
3. Department of General Practice, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
4. Dutch Cochrane Centre, Amsterdam, The Netherlands
5. Netherlands Trial Register, Amsterdam, The Netherlands
6. Department of Epidemiology, Biostatistics, and Health Technology Assessment, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
7. Medical Library, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands