There is also a two volume work about this topic, published by German "Flugzeug" Verlag;
the books are called "Die deutschen Flugzeuge in russischen und sowjetischen Diensten" and both are written by authors Alexandrov and Petrov;
they may be hard to get, but if you are interested, I think my local book dealer still has some available; AFAIK, both together retail for only 25 Euros, so if you are interested, let me know
best regards
phil
ps.: here is a link to amazon.de for those books
http://www.amazon.de/s/ref=nb_ss_w/0...0&Go.y=0&Go=Go