Came across them for the first time while playing S.T.A.L.K.E.R. Anomaly, and found them interesting.
Most of these seem to be from the late Soviet Union era. Could be wrong, though. Uploaded the .zip to catbox: link
From the very very little digging I did, track_15.ogg is Spokoynaya noch by the band Кино (Kino). Some of the other tracks here might also be from Кино. Anyone able to ID the rest?
Did you try them on song-identifying services, like SoundHound and Shazam? I’ve had a lot of success with them.