Author(s):
1. Ljubica Vasiljević, Faculty of Technology - University of East Sarajevo,
Republic of Srpska, Bosnia and Herzegovina
2. Dragana Kešelj,
Republic of Srpska, Bosnia and Herzegovina
3. Jelena Penavin-Škundrić, Prirodno-matematički fakultet Banja Luka,
Republic of Srpska, Bosnia and Herzegovina