1. N. I. Bazilevich, Biological Productivity of Ecosystems in the Northern Eurasia (Nauka, Moscow, 1993) [in Russian].
2. N. I. Bolotina, “Humus and Nitrogen Reserves in the Main Soil Types of the Soviet Union,” in Agrochemical Characterization of Soils of the Soviet Union (1976), pp.187-202.
3. Great Soviet Atlas of the World (Moscow, 1937), Vol. 1, Maps 122–123 [in Russian].
4. I. F. Golubev, Soil Science with Basic Geobotanics (Kolos, Moscow, 1970) [in Russian].
5. S. D. Gusev, Vegetation and Dynamics of the Overgrowing of Long-Fallow Lands in the Verkhnii Ural Region (Ural’skii Kraeved, Nadezhdinsk, 1932) [in Russian].