1. Military Medical Academy, Department of Abdominal Surgery, Belgrade, Serbia + University of Defence, Faculty of Medicine of the Military Medical Academy, Belgrade, Serbia
2. Military Medical Academy, Department of Abdominal Surgery, Belgrade, Serbia
3. University of Defence, Faculty of Medicine of the Military Medical Academy, Belgrade, Serbia + Military Medical Academy, Institute for Transfusiology and Haemobiology, Belgrade, Serbia
4. University of Kragujevac, Faculty of Medical Sciences, Department of Internal Medicine, Kragujevac, Serbia