Barbara Bielowicz (2017). THE CONTENT OF RADIOACTIVE ELEMENTS IN THE POLISH LIGNITE AND ITS ASHES. SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 17th International Multidisciplinary Scientific GeoConference SGEM2017, Science and Technologies in Geology, Exploration and Mining, 597-604. https://doi.org/10.5593/sgem2017/11/s01.075