1 Surgery Department, Faculty of Medical Sciences, University of KragujevacKragujevac, Serbia; Surgery Clinic, Clinical Centre KragujevacKragujevac, Serbia.
2 Faculty of Science, Institute of Biology and Ecology, University of Kragujevac Kragujevac, Serbia.
3 Department of Medical Statistics and Informatics, Faculty of Medical Sciences, University of Kragujevac Kragujevac, Serbia.