Vienna and spies

Can anyone give me some tips on spynovels set in Vienna? Is there a spynovel about Vienna, like "The spy who came in..." for Berlin?
Thanks

It depends on how you define "spy". The classic adventure thriller made into a film noir is Graham Greene's screenplay for The Third Man, though it was never intended as a separate novel, and is not a conventional "spy" story - though it seems very much in the same genre as the 60s spy novels by Len Deighton which were turned into movies starring Michael Caine.

Another unconventional quasi-spy story is A Death In Vienna by Daniel Silva, which unfolds into a Holocaust story.

Prelude to Terror by Helen MacInnes is spy story set in Vienna, and of course The Salzburg Connection is also taking place in Austria.