Downloadable sheet music for any of Arno Babajanyan's works are pretty thin on the ground, but you can find his Nocturne in B Minor at scorser.com/S/Sheet+music, both for piano and piano & orchestra.
Apart from those sites, Babajanyan sheet music seems in short supply, perhaps a consequence of his being not so well known outside of his native Armenia or the greater Russian region.
A possible way around this is to try Google Images, and entering, for example, 'Nocturne in B Minor Babajanyan' and then clicking on the images that come up. This can lead you to websites that don't necessarily come up on the standard text-based Google search.
Another tactic may be to join a classical music online forum, and post a question asking for help. Talkclassical.com and classicalmusicguide.com are two popular places you might like to try.
YouTube users could also help. Why not leave a comment requesting help under one of the filmed performances of the piece, such as this one?
