Степанова, К. Д., and С. В. Петров. “Material Composition of Calcite Carbonatites of the Kovdor Massif That Are Potential Industrial Ores”. Proceedings of Voronezh State University. Series: Geology, no. 1, Feb. 2018, pp. 102-8, doi:10.17308/geology.2018.1/1442.