Russian Abstract Expressionist School - Oil Painting 20th Century

A very impressive abstract expressionist painting of a cityscape.  Oil on card. 

Signed at the lower right corner though I am unable to make out the artist's name.  Stylistically it appears to be of the 1950s period.  Looking at the reverse you can see it has been removed from it's frame at some point.  Hopefully, someone may be able to decipher the signature (see close up photo) or recognise the style.  (Original owner's name on reverse of card?)

Dimensions: 51 cm x 36 cm