00554naa#a2200181#i#450# EN\\bibl\46547 20260314140535.6 1681-1208 20201225b2020####ek#y0engy0150####ca ENG RU The aspects of K-index calculation at Russian Geomagnetic Observatories Journal article Moscow Geophysical Center of the Russian Academy of Sciences 2020 0 с. Journal article local Petrov Valery G Krasnoperov Roman I ras.editorum.ru