BERNSTEIN, LEONARD. (1918-1990). American composer, conductor, pianist, music educator; one of the most prodigiously talented and successful musicians in American history. Attractive Autograph Musical Quotation Signed: “Leonard Bernstein / Clarinet Sonata”, in red ink, on a small oblong octavo card stock imprinted with a musical staff. Bernstein has penned the first 3 bars of music form his composition. Pencil notation on verso says the autograph was obtained in November 1971. Very fine condition and not often encountered.