1. Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
2. Institute of Hygiene, Military Medical Academy, 11000 Belgrade, Serbia
3. Clinic for Neurosurgery, University Clinical Center of Serbia, 11000 Belgrade, Serbia
4. Medical Faculty of the Military Medical Academy, University of Defence, 11000 Belgrade, Serbia
5. Clinic for Neurosurgery, Military Medical Academy, 11000 Belgrade, Serbia
6. School of Public Health and Health Management, University of Belgrade, 11000 Belgrade, Serbia
7. Institute of Social Medicine, University of Belgrade, 11000 Belgrade, Serbia