Future of oil shale mining technology in EstoniaKaru, Veiko; Västrik, Aire; Anepaio, Ain; Väizene, Vivika; Adamson, Alo; Valgma, IngoOil shale2008 / 2S, p. 125-134 : ill https://www.researchgate.net/publication/220009289_Future_of_Oil_Shale_Mining_Technology_in_Estonia