• Oil shale mining developments in Estonia as the bases for sustainable power industryValgma, Ingo; Karu, Veiko; Viil, Allan; Lohk, Martin4th International Symposium Topical Problems of Education in the Field of Electrical and Power Engineering. Doctoral School of Energy and Geotechnology : Kuressaare, Estonia, January 15-20, 20072007 / p. 96-103 : ill