1. Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
2. Swiss Paraplegic Research, Nottwil, Switzerland
3. Department of Epidemiology, Erasmus MC, Rotterdam, the Netherlands
4. Public Health & Primary Care Library, University Library of Bern, University of Bern, Bern, Switzerland
5. Nutrition Innovation Center, Standard Process Inc, Palmyra, Wisconsin, USA