1. Health Systems Based on Primary Health Care (HSS), Pan American Health Organization; Research Promotion and Development Team; 525, 23rd St, NW Washington DC USA 20037-2895
2. University of the Basque Country; Department of Preventive Medicine and Public Health. GIU 10/24.; Barrio Sarriena S.N. Leioa Bizkaia Spain E-48080
3. Institute of Oncology, Fundación Santa Fe de Bogotá; Clinical and Translational Oncology Group; Calle 119 No. 7 - 75 Bogotá Cundinamarca Colombia 0571