Grazyna Wojcik (2017). SIX SIGMA AS THE METHOD OF PROCESSES- EFFICIENCY IMPROVEMENT IN ENERGY INDUSTRY. SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; SGEM2017 17th International Multidisciplinary Scientific GeoConference, 773-780. https://doi.org/10.5593/sgem2017/53/s21.096