1. Leskovac General Hospital, Leskovac, Serbia
2. Narodni Front Clinic for Gynecology and Obstetrics Belgrade, Serbia
3. Clinic for Anesthesiology and Intensive Care, Clinical Center of Vojvodina, Novi Sad, Serbia
4. SUNY Downstate Medical Center, Brooklyn, New York, United States of America
5. Memorial Regional Hospital, Hollywood, Florida, United States of America