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2. A. F. Vadyunina and Z. A. Korchagina, Methods for Studying Soil Physical Properties (Agropromizdat, Moscow, 1986) [in Russian].
3. L. A. Vorob’eva, Theory and Practice of the Chemical Analysis of Soils (GEOS, Moscow, 2006) [in Russian].
4. Steppe kurgans: a unique historical-natural archive;V. A. Demkin,2000
5. L. L. Shishov, V. D. Tonkonogov, I. I. Lebedeva, and M. I. Gerasimova, Classification and Diagnostic System of Russian Soils (Oikumena, Smolensk, 2004) [in Russian].