1. Agrochemical Methods of Soil Study, Ed. by A. V. Sokolov (Moscow, 1975) [in Russian].
2. E. E. Andronov, A. G. Pinaev, E. V. Pershina, and E. P. Chizhevskaya, Scientific and Methodological Recommendations for the Isolation of Highly Purified DNA Preparations from Environmental Objects (St. Petersburg, 2011) [in Russian].
3. L. G. Bakina, Extended Abstract of Doctoral Dissertation in Biology (St. Petersburg, 2012).
4. D. G. Zvyagintsev, Soil and Microorganisms (Mosk. Univ., Moscow, 1987) [in Russian].
5. A. G. Zavarzina, N. N. Danchenko, V. V. Demin, Z. S. Artemyeva, and B. M. Kogut, “Humic substances: hypotheses and reality (a review),” Eurasian Soil Sci. 54 (12), 1826–1854 (2021). https://doi.org/10.1134/S1064229321120164