00604naa#a2200181#i#450# EN\\bibl\47321 20240426210933.5 2500-3372 20211122b2021####ek#y0engy0150####ca RU E-learning Systems in the Russian Mining and Metallurgical Sector Journal article Kemerovo Kemerovo State University 2021 10 с. Journal article local Статистика. Демография. Социология. 31 Kazakova M. I. Selivanova Tat'yana Vladimirovna vestnik-pses.kemsu.ru