1. Institute for Emergency Medical Centre , Kragujevac , Serbia
2. Clinic for Pulmonary Diseases, Clinical Centre Kragujevac , Kragujevac , Serbia
3. University of Kragujevac, Faculty of Medical Sciences , Department of Internal medicine , Kragujevac , Serbia
4. Cardiology Clinic , University Clinical Centre Kragujevac , Serbia
5. Faculty of science , Kragujevac , Serbia
6. Institute for Health Protection of workers Zastava , Kragujevac , Serbia