Just saw on another board that Roger Freeman, WW2 aviation author passed away. His best and most important work I think was "The Mighty Eighth" about the 8th AF in WW2. My copy has been used to the point of falling apart. He wrote two other works on the 8th to complete a trilogy on it as well as numerous other books that are part of the back bone of any good aviation history library.
If you haven't read his stuff, it's well worth the time to track it down.