1] mr Gregor Uranjek SAFETY MEASURES AT COAL EXTRACTION IN VELENJE COAL MINE IN ORDER TO PREVENT THE EFFECTS OF SUDDEN INRUSHES AND OUTBREAKS OF COAL GASES" - 7. Balkanski rudarski kongres, 15.05.2017.
(https://ekonferencije.com/sr1/rad/safety-measures-at-coal-extrac/5031)