Baigenzhenov, O., S. Yulussov, Khabiyev А., Sydykanov М., and M. Akbarov. “Investigation of the Leaching Process of Rare-Earth Metals from the Black Shale Ores of Greater Karatau”. Kompleksnoe Ispolzovanie Mineralnogo Syra = Complex Use of Mineral Resources, vol. 310, no. 3, Sept. 2019, pp. 76-80, doi:10.31643/2019/6445.31.