In my view, your first port of call should be the Schiffer Publishing catalogue. Much of their stuff is written from a German perspective, but if you can live with that, try Paul Carell's two volumes that deal with the campaign from 1941 to the collapse of Army Group Centre in 1944; also look at the semi-autobiographical stuff by Alex Buchner. Perhaps the best single-volume work is Albert Seaton, The Eastern Front 1941–5, even if it's getting a bit long in the tooth.
Avoid Clark and Erickson; both write tendentious rubbish. Neither is capable of differentiating between the Nazis and the German armed forces, and therefore may be capable of writing impassioned political history, but not military history.