Author(s):
1. Božidar Ilić, Republic of Srpska, Bosnia and Herzegovina
2. Saša Zeljković, Prirodno-matematički fakultet Banja Luka, Republic of Srpska, Bosnia and Herzegovina
3. Svjetlana Zeljković, University of Banja Luka, Faculty of Architecture, Civil Engineering and Geodesy, Bosnia and Herzego, Republic of Srpska, Bosnia and Herzegovina