Future of oil shale miningValgma, Ingo; Karu, Veiko; Västrik, Aire; Väizene, Vivika15th Meeting of the Association of European Geological Societies "Georesources and public policy : research, management, environment" : 16-20 September 2007, Tallinn, Estonia : abstracts2007 / p. 81 https://www.ester.ee/record=b2291667*est