'Germany and the Second World War' Vol vii, The strategic Air War in Europe and the War in the West and East Asia 1943-1944/5; Boog, Krebs and Vogel.

Although translated by people not unduly worried by aesthetics the narrative and analysis is top notch. I was led to this by Adam Tooze's footnotes and bibliography in 'The Wages of Destruction'. Only 200 pages of 700 odd to go then it's Vol iv.