1. Clinic for Pulmonology, University Clinical Center of Serbia, 11000 Belgrade, Serbia
2. Medical Faculty, University of Belgrade, 11000 Belgrade, Serbia
3. Clinic for Digestive Surgery, First Surgical University Hospital, Clinical Centre of Serbia, 11000 Belgrade, Serbia
4. Center for Radiology and MR, University Clinical Center of Serbia, 11000 Belgrade, Serbia
5. Institute for Medical Statistics and Informatics, University of Belgrade, 11000 Belgrade, Serbia