@inproceedings{sgem2019s06134,
  title = {POWER FLUCTUATION INDEX (PFI) - A METHOD OF EVALUATING THE EFFICIENCY AND QUALITY OF PERFORMED HORIZONTAL DIRECTIONAL DRILLING (HDD)},
  author = {Jаn Zіаjа},
  booktitle = {SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 19th SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings19th, Science and Technologies in Geology, Exploration And Mining},
  year = {2019},
  pages = {1053-1060},
  publisher = {STEF92 Technology},
  doi = {10.5593/sgem2019/1.2/s06.134}
}