Piano Concerto for the Left Hand - Ravel
Maurice Ravel (1875-1937), was a French composer of Impressionist and Early 20th Century music.
Ravel completed Piano Concerto for the Left Hand in 1930.
To learn more about the composer, visit Maurice Ravel on Wikipedia.
For more on the composition, visit Piano Concerto for the Left Hand - Ravel on Wikipedia.
Performance
Maurice Ravel - Piano Concerto for the Left Hand
Excerpts
Ravel - Piano Concerto for the Left Hand audio excerpts are available on The Trombone Clips Youtube channel.
Trombone Parts and Full Score
The full score of Piano Concerto for the Left Hand is available on IMSLP.org.
NOTE: IMSLP provides access to public-domain scores and parts, with copyright status varying by country. Users are responsible for observing applicable copyright laws.
Trombone parts are available on IMSLP.org as follows:
Ranges and clefs by Part

More Ravel
Trombone Resources playlist of Ravel with Trombones in the instrumentation.