1. 1 The University of Novi Sad , Technical faculty “Mihajlo Pupin” , Zrenjanin , Serbia
2. 2 University “Union Nikola Tesla” , Faculty of Engineering Management , Belgrade , Serbia
3. 3 The University of Novi Sad , Faculty of Economics , Subotica , Serbia
4. 4 The University “Union Nikola Tesla” , Beograd, Faculty of Management , Sremski Karlovci , Serbia
5. 5 The University of Kragujevac , Faculty of Technical Sciences , Čačak , Serbia