Here are four CDs of Anton Karas, famous for his zither playing in "The Third Man:"

Wiener Klänge [Sounds of Vienna] (1991 German CD issue) - selection of Viennese folk / classical tunes performed by Karas on the zither accompanied by orchestra. German CD reissue/release of LP material. Sound quality is very limited in dynamic range and response by modern standards. Although dated 1991, it sounds like it was recorded in the 1950s - on a portable cassette recorder from Radio Shack - in a cave - with the one microphone under a pillow.

Around the World with Anton Karas (1997 - Switzerland) - a collection of mainly European tunes (with an interesting rendition of "The River Kwai March"). Fidelity here is good, in stereo.

Anton Karas - a fairly modern recording (1991 - Japanese issue) of German, Austrian, and a few other European tunes, including the hit song from the film "Never on Sunday."

The Third Man - Original Soundtrack (1949):  self-explanatory; from the British/American film starring Orson Welles, Joseph Cotton, Alida Valli, Trevor Howard, and Ernst Deutsch :
     
Favorite quote from the film:
"In Italy for thirty years under the Borgias they had warfare, terror, murder,  bloodshed—but they produced Michelangelo, Leonardo da Vinci, and the Renaissance. In Switzerland they had brotherly love, 500 years of democracy and peace, and what did that produce? The cuckoo clock."  Harry Lime 

Enjoy...