Efremov, S., Nechipurenko, S., Kazankapova, M., Washington, W., Tassibekov, K., & Nauryzbaev, M. (2013). Physico-Chemical Characteristics of Shungite Rock of Kazakhstan. Eurasian Chemico-Technological Journal, 15(3), 241-249. https://doi.org/10.18321/ectj228