@inproceedings{sgem2006paper,
  title = {EXPLOITATION OF THICK COPPER ORE DEPOSITS BY DOUBLE- LAYER ROOM AND PILLAR METHOD},
  author = {J. Butra and R. Debkowski and J Kudelko and J. Nowak},
  booktitle = {6th International Scientific Conference - SGEM},
  year = {2006},
  pages = {35-42},
  publisher = {SGEM Scientific GeoConference},
  doi = {}
}