1. Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria.
2. European Centre for Disease Prevention and Control, Stockholm, Sweden.
3. Department of Medical Informatics, Academic Medical Center, Amsterdam, The Netherlands.
4. Department of Biomedical Engineering, Linköping University, Linköping, Sweden.
5. National Library of Medicine, National Institutes of Health, Bethesda, MD, USA.