Question: The 1909 "The Count of Luxemburg" was by a composer whose best known and most successful operetta was what?
Sentence (from "The Count of Luxemburg (1957 film)"): The Count of Luxemburg (German: Der Graf von Luxemburg) is a 1957 West German musical comedy film directed by Werner Jacobs and starring Gerhard Riedmann, Renate Holm and Gunther Philipp.
Relevant evidence: No