00546naa#a2200181#i#450# EN\\bibl\46547 20240503084655.5 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 rjes.ru