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In May 2022 ICRANet organized the Workshop dedicated to the 80th anniversaryof Professor Ruffini. This paper is based on the talk delivered at the meeting.  Professor Ruffini was well known for Soviet scientific community not only dueto his publications in leading journals but also due Russian translations ofhis books where he was an author or a contributor in collection of articles.  But only in 1988 I had an opportunity to watch and listen professor R.Ruffini at the Conference dedicated to the century since the birthday ofAlexander Alexandrovich Friedmann. This conference was organized in Leningrad(Soviet Union) in June during a short magic period when there are white nightsthere. In June 2023 we celebrate the 135th anniversary of Friedmann's birth.Friedmann and his closed friend V. K. Frederics were the founders of Sovietschool of general relativity and George Gamow was one of the brilliantrepresentative of the school and he was the author of the hot Universe modelwhich is the most popular now. In the USSR a development of general relativityand relativistic cosmology was not smooth and only in sixties of the lastcentury these branches of science freed from the total control ofrepresentatives of the ideology of Marxism -- Leninism. I also discussed aSoviet contribution in a discovery of cosmic microwave background radiationdone by T. Shmaonov in 1957 and reasons why his supervisors did not connectthese results with the hot Universe models discussed by G. Gamow. Author'sresults about observational features of supemassive black holes (including theblack hole in our Galactic Center) are also briefly discussed, it wasconsidered  an opportunity to evaluate a (tidal) charge of Reissner -- Nordstr\"om blackhole from observational estimates of shadow size in the Galactic Center andM87* done by the EHT Collaboration based its observations in April 2017.

Constraints on black hole charges in M87* and Sgr A* with the EHT observations