1. Institute Niska Banja, Medical Faculty, University of Nis, Nis, Serbia
2. Clinical Hospital Bezaniska Kosa, University Belgrade School of Medicine, Belgrade, Serbia
3. Medical Faculty, University of Nis, Nis, Serbia
4. Asklepeion Hospital, Athens, Greece
5. Cardiology Department, University of Athens, Athens, Greece
6. Clinic for Internal disease Intermedica, Nis, Serbia