Helped establish the authorship of the monogram
 

please help to establish the authorship of monogramme.eto portrait of Professor NN Kachalova ch.k.AN USSR, size 45 * 38cm, paper, charcoal, sanguine, and chalk (or bed). monogram GS or date R.Sh.i 53

N. N. Kacalov bil pianistom?

He was a scientist.
Memorial plaque. Sculptor NA Sokolov, 1964.

more like PI.
Suddenly - Peter Ignatiev?

He was a leading Soviet specialist in the manufacture of optical glass (http://www.encspb.ru/persarticle.php?kod=2803925839), I add that his wife was famous in his time prima Aleksandrinsky ( after Pushkin) Theater Elizabeth I. Thieme.

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redbor, thank you, a valuable observation, such a variant reading not come into my head

Hello
Apparently, we have work Peter Mitrofanovich Shuhmina (1894-1955), probably the author's repetition.
Signature characteristic of his later works
portrait Academician Kachalova in the same technique he performed in 1950 (in the book Razumovskaya S. Peter Shuhmin, L., 1966 is this date)
(44h39, boom., Sanguine, chalk, charcoal, property of E. Time, exhibited 1964)
You can see his exhibition catalog (Catalog of the exhibition of works Shuhmina. The introductory article by P. Razumovsky, 1964)

Leningrad, thank you. this work is really a collection of E. Time and N. Kachalova. After the death of Elizabeth Ivanovna, she was her niece. likely it is that same work, which was at the exhibition Shuhmina, since the dimensions as quoted by you

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