Author(s):
1. Milanka Negovanović, University of Belgrade, Faculty of Mining and Geology, Serbia
2. Lazar Kričak, University of Belgrade, Faculty of Mining and Geology, Serbia
3. Dražana Tošić, Univerzitet u Banjoj Luci,
Republic of Srpska, Bosnia and Herzegovina
4. Snežana Ignjatović, University of Belgrade, Faculty of Mining and Geology, Serbia