Original: In February 1914, at age eleven, he made his concert debut, playing Joseph Haydn's Cello Concerto in D major with the Vienna Philharmonic conducted by Felix Weingartner.
Simplified: In February 1914, aged twelve, he played in his first concert, performing Joseph Haydn's Cello Concerto in D with the Vienna Philharmonic conducted by Felix Weingartner.