Author(s):
1. Ana Simović, University of Kragujevac, Faculty of Science, , Serbia
2. Svetislav Savović, Univerzitet u Kragujevcu, Prirodno-matematički fakultet, , Serbia
3. Aco Janicijević, Tehnološko-metalurški fakultet, Univerzitet u Beogradu, Srbija, Serbia
4. Alexandar Djordjevich, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong Hong Kong, Kowloon, Hong Kong
5. Branko Drljača, PMF Kosovska Mitrovica, Serbia

Abstract