1. M. M. Kononova, Soil Organic Matter (Akad. Nauk SSSR, Moscow, 1963) [in Russian].
2. E. Yu. Milanovskii, “Amphiphilous components of soil humic substances,” Eurasian Soil Sci. 33(6), 617–625 (2000).
3. E. Yu. Milanovskii, Humic Substances as the Natural Hydrophilic-Hydrophobic Compounds (GEOS, Moscow, 2009) [in Russian].
4. D. S. Orlov, Humic Acids and a General Theory of Humification (Moscow State Univ., Moscow, 1990) [in Russian].
5. L. A. Osterman, Methods to Study Proteins and Nucleic Acids. Electrophoresis and Ultracentrifugation (Nauka, Moscow, 1981) [in Russian].