1. L. A. Aleksandrova, Soil Organic Matter and Processes of Its Transformation (Nauka, Leningrad, 1980) [in Russian].
2. N. P. Bityutskii, Essential Plant Microelements (DEAN, St. Petersburg, 2005) [in Russian].
3. Yu. N. Vodyanitskii, Iron Compounds and Their Role in Soil Protection (Pochv. Inst. im. V. V. Dokuchaeva, Moscow, 2010) [in Russian].
4. V. I. Golov, Cycle of Sulfur and Microelements in the Main Agroecosystems of the Far East (Dal’nauka, Vladivostok, 2004) [in Russian].
5. E. A. Dmitriev, Mathematical Statistics in Soil Science (Librokom, Moscow, 2009) [in Russian].