Author(s):
1. Blagica Doneva, University of Goce Delcev, Faculty of natural and technical sciences, Macedonia
2. Todor Delipetrov, Faculty of natural and technical sciences, Macedonia
3. Marjan Delipetrev, University of Goce Delcev, Faculty of natural and technical sciences, Macedonia
4. Krsto Blazev, University of Goce Delcev, Faculty of natural and technical sciences, Macedonia
5. Gorgi Dimov, University of Goce Delcev, Faculty of natural and technical sciences, Macedonia

Final paper