1. Institute of General Practice and Family Medicine; Center of Health Sciences, Martin Luther University Halle Wittenberg; Halle (Saale) Germany
2. Department of Preventive Medicine; School of Public Health, Addis Ababa University; Addis Ababa Ethiopia
3. Institute for Medical Knowledge Management; Association of the Scientific Medical Societies in Germany, Berlin, c/o Philipps University Marburg; Berlin & Marburg Germany
4. Norwegian Institute of Public Health; Oslo Norway