sentences:  Subsequently, he performed chamber music with Pablo Casals, Mischa Elman, Jascha Heifetz, Fritz Kreisler, Gregor Piatigorsky, Efrem Zimbalist and Alfredo Rossi.He was an accomplished violinist, playing 15-minute radio recitals when he was asked to play the soundtrack for Ernst Lubitsch's movie "The Merry Widow"; this performance opened up a long career in performing soundtracks for Hollywood films, including such classics as "Casablanca", "Gone with the Wind", "The Diary of Anne Frank", "Wuthering Heights", "The Grapes of Wrath", and "Spartacus".It is variously estimated that he made 400 solo performances for movies and acted as the concertmaster for several hundred.