[RuffMonk]

Well if you're looking for pure historical information, then I'd have to suggest the Eastern Front air battle series by Christer Bergstrom which I used to generate my Battle of Stalingrad historical missions. They go into GREAT detail about the aerial engagements as well as the ground battles as well! They are full of great illustrations and actual WWII photos throughout the entire read for each book. I've only read the first three however, but I can only imagine that the last is just as good though.

- Barbarossa: The Air Battle: July - December 1941
- Stalingrad: The Air Battle: November 1942 - January 1943
- Kursk: The Air Battle: July 1943
- Bagration to Berlin: The Final Air Battles in the East 1944 - 1945

Another great read for historical information which I'm currently using for my Sicily series is "Messerschmidts Over Sicily" by Johannes Steinhoff which chronicles his brief stint in the Mediterranean. It's based off of the war diary he kept while serving with the Luftwaffe and is very descriptive and well written.

Lastly, again for purely historical information would be the "Air War Chronology, 1939 - 1945" by Myron J. Smith Jr. which is a volume of books that I think is supposed to cover every documented aerial engagement in all theaters during WWII. I stumbled across a portion of this series in a University library while looking for historical sources in which to base my Sicily series upon. It breaks down each day of the war by theater and then gives a brief overview of the engagement which includes the aircraft that were involved, the action they took and in some case the response from the opponent. For example here is one entry that I'm using for the second battle in my historical series:

July 4 1943
Mediterranean 11579) Escorted by 1st and 14th FG P-38s, US 2nd, 97th, 99th and 301st BG (H) B-17s assail Gerbini aerodrome.