On 25 September, Dmitri Shostakovich's birthday, it was announced that a previously unknown composition of this composer was found in Moscow’s central archive,

It is a short work for viola and piano, titled Impromptu op. 33. The piece was found among documents belonging to Vadim Borisovsky, the violist of the Beethoven Quartet, who died in 1972.

On the title page is written that is was composed 2 May 1931, in Leningrad. Shostakovich then was 24. The dedication is to "Alexander Mikhailovich", who is beleived to be Alexander Ryvkin, violist of the Glazunov Quartet.

source: https://www.thestrad.com/news/a-new-work-for-viola-by-shostakovich-disco...