1. Professor, Faculty of Technical Sciences, Univ. of Kragujevac, Svetog Save 65, 32000 Cacak, Serbia.
2. Professor, Technical faculty “Mihajlo Pupin”, Univ. of Novi Sad, Zrenjanin, Djure Djakovica bb, 23000 Zrenjanin, Serbia.
3. Professor, Faculty of Occupational Safety, Dept. of Environmental Protection, Univ. of Niš, Carnojevica 10a, 18000 Nis, Serbia (corresponding author).
4. Professor, Faculty of Occupational Safety, Dept. of Environmental Protection, Univ. of Nis, Carnojevica 10a, 18000 Nis, Serbia.