1. Stevenson, F.J., Humus Chemistry, New York: Wiley, 1994, 2nd ed.
2. Dobbs, L.B., Canellas, L.P., Olivares, F.L., et al., Bioactivity of chemically transformed humic matter from vermicompost on plant root growth, J. Agric. Food Chem., 2010, vol. 58, no. 6, pp. 3681–3688.
3. Zherebtsov, S.I. and Ismagilov, Z.R., Effect of the alkylation of brown coal and peat on composition and properties of humic acids isolated from them, Solid Fuel Chem., 2012, vol. 46, no. 6, pp. 339–351.
4. Malyshenko, N.V., Zherebtsov, S.I., Smotrina, O.V., et al., Sorption of zinc cations by modified humic acids, Chem. Sustainable Dev., 2015, vol. 23, no. 4, pp. 451–457.
5. Komissarov, I.D. and Loginov, L.F., Electron paramagnetic resonance in humic acids, in Guminovye kisloty (Humic Acids), Tyumen: Tyumen. S-kh. Inst., 1971, vol. 14, pp. 70–74.