Need help finding information about War Atrocities committed by Russia during WWII. Any Help?

I've linked several articles below for your review. 1st - Ethnic cleansing, 2nd is an overview on Allied war crimes, 3rd a specific record of the details on the previous posters Katyn macre. There were significant atrocities committed before (1932-33 era in the Ukraine) and after (Stalin's pogroms) the war and with most focus on the Nuremberg trials a lot of Allied crimes either went un-or-under reported. Best of luck in your research, hope this helps.