1. Clinic for Cardiology and Emergency Internal Medicine, Military Medical Academy, School of Medicine University of Defense Belgrade Serbia
2. Institute for Pulmonary Diseases of Vojvodina, Clinic for Pulmonary Oncology, Faculty of Medicine University of Novi Sad Novi Sad Serbia
3. Clinic for Cardiology, Clinical Center Nis, School of Medicine University of Nis Serbia
4. Clinic for Cardiology, School of Medicine University of Kragujevac Serbia
5. Zvezdara University Medical Center, School of Medicine University of Belgrade Serbia
6. Clinic for Cardiology, Clinical Center Banja Luka, School of Medicine University of Banja Luka Banja Luka Bosnia and Herzegovina