I apologize if this question does not really fit here.
I appreciate if someone can suggest math research articles in Russian (to practice reading, learning some math related terminologies etc.)
I don't want to restrict any subject or level of difficulty, but I prefer an original work which will be interesting to read. Many thanks.
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Try Успехи математических наук (which is translated in English as Russian Mathematical Surveys).
http://www.mathnet.ru/php/journal.phtml?jrnid=rm&option_lang=rus
and in particular their archive, where you get free access to articles three years old or older:
http://www.mathnet.ru/php/archive.phtml?jrnid=rm&wshow=contents&option_lang=rus
It publishes research on various math areas, and as to picking work interesting to read, you are on your own, browse the archive, titles and abstracts.
I have occasionally read math papers in Russian in the past (learned Russian in school in Bulgaria years ago). In particular some interesting ones to me in the area of general topology, a very old Memoir (from the 1920's) by Alexandroff and Urysohn, a more recent 1970's paper by Mischenko about Linerly Lindelof spaces (finally compact, forgot the entire term, in Russian). In general, at least for older papers, but also new ones, some of the terminology is different, e.g. bicompact (instead of compact), finally compact (instead of Lindelof), and I don't know much about other areas. I am pretty sure you could find more journals like that, but this was the first one for me to think about (I may look for more later).
Well, actually here is another well-known one,
Математические заметки (Mathematical Notes):
http://www.mathnet.ru/php/journal.phtml?jrnid=mzm&option_lang=russian
and its archive
http://www.mathnet.ru/php/archive.phtml?jrnid=mzm&wshow=contents&option_lang=rus
And (on the same general website) they have a list of other journals.
http://www.mathnet.ru/ej.phtml?option_lang=eng
or (in Russian)
http://www.mathnet.ru/ej.phtml?option_lang=russian
Good luck!
A nice bite-sized place to start would be the Международная Математическая Oлимпиада: https://www.imo-official.org/?language=ru.
Click on задачи, then for most recent years you can download the problems in the language of your choice. Удачи!
Update: for articles, consider the publication Квант. It was a popular science magazine aimed at school students and teachers, and its archives are freely available. Here's the collection of its mathematics articles: http://kvant.mccme.ru/rub/19A.htm