Interlude and Polish Song from the operetta "Die blaue Mazur" ("The Blue Mazurka") Interlude and Polish Song from the operetta "Die blaue Mazur" ("The Blue Mazurka") Main opus "Die blaue Mazur" ("The Blue Mazurka"), operetta in 2 acts and 1 interlude, libretto by Leo Stein and Béla Jenbach