time for a pot of black coffee and some fresh air 

G. I. Kirosheev Soviet Casualties and Combat Losses. Greenhill 1997 ISBN 1-85367-280-7 lists
the following official losses ( the data quoted by Overy) Killed in Action and dead of wounds
6,330,000; non combat deaths 556,000. Those are confirmed losses reported to the high command by the fronts. Estimated MIA were 500,000 and estimated POW dead 1.3 million. The grand total was 8.6 million. What a coincidence that this is exactly the same as Axis losses of 8.6 million as reported in Kirosheev. The USSR losses were equal to the Axis on the Eastern front, right or wrong? Pow loses were 1.3 million, right or wrong? Check your numbers before you make a change. 
Real losses of Pows were about 2.8 million and MIA were 500,000. Add that to 6.9 million confirmed dead and you are at 10.4 million. That does not include losses of Partisans and Milita of 400,000 ( they must be included as military not civilian losses). Berndd