1. Mathematical Institute, The Serbian Academy of Sciences and Arts, Kneza Mihaila 36, Belgrade 11000, Serbia
2. Aeronautical Department, The Military Technical Institute, Ratka Resanovića 1, Belgrade 11000, Serbia
3. Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181/A, Parma 43124, Italy
4. Faculty of Mathematics, University of Belgrade, Studentski trg 16, Belgrade 11000, Serbia