Battle for Vienna 1945 Sources?

[Abwehrschlacht]

as my wife works in Vienna now, I have had a chance to visit quite a few times and as usual that has sparked an interest in the city's role in the Second World War. I know a little about the fighting there and the flak towers that are still visible in the city, but does anyone know of any good English language books on the actual fighting in April '45? Most histories appear to brush over it.