American composer trombonist conductor and teacher David Uber (b. 1921) is a virtuoso performer on the Trombone as well as a popular music professor. His 23 Virtuoso Clef Studies remain significant for Trombone Baritone Euphonium and Tenor Tuba players. Uber 's 23 Virtuoso Clef Studies were compiled in 1982 and address advanced musical techniques including unusual time signatures complex rhythms accidentals variations in performance directions breath control unusual intervals complex key signatures ornamentation and articulation among other aspects. For all advanced Trombone Baritone Euphonium andTenor Tuba players Uber 's 23 Virtuoso Clef Studies ensure progressive technical studies.