1. Clinic for Digestive Surgery, Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
2. Department of Surgery, University Hospital Southampton, Southampton, UK
3. Institute for Biostatistics and Informatics, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
4. Clinic for Emergency Surgery, Emergency Center, Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
5. Clinic for Surgery, Military Medical Academy, Belgrade, Serbia
6. Clinic for Surgery, Clinical Center “Bezanijska Kosa”, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
7. Clinic for Surgery, Clinical Center “Zvezdara”, Belgrade, Serbia