1. E. A. Afanas’eva, Chernozems of the Central Russian Upland (Nauka, Moscow, 1966) [in Russian].
2. B. P. Akhtyrtsev and I. A. Lepilin, “Changes in the physical and hydrological properties of leached chernozems of the Oka–Don Lowland under the impact of intensive farming” in Rational Use of Land Resources and Improvement of Soil Fertility (Mordovian State Univ., Saransk, 1985), pp. 61–76.
3. T. L. Bystritskaya and M. I. Gerasimova, “Annual cycle of modern processes in chernozems,” Pochvovedenie, No. 6, 5–15 (1988).
4. P. V. Vershinin and I. B. Revut, “Structure and physical conditions of soils in the Kamennaya Steppe,” Tr. Agron. Fiz., No. 6, 5–56 (1953).
5. V. R. Williams, Fundamentals of Farming (Sel’khozgiz, Moscow, 1948) [in Russian].