European Axis Signal Intelligence in World War IIAs Revealed by "TICOM" Investigations and by Other Prisoner of War Interrogations and
Captured Material, Principally German. In Nine Volumes. Chief, Army Security Agency
They can be found online at the NSA website : http://www.nsa.gov/public_info/declass/european_axis_sigint.shtml
I don't know of a better source for the history and achievements of the German codebreakers .