Really Easy Trombone Book: Trombone: Instrumental Album
If you can play just a few notes on the Trombone (or Euphonium) then you're ready for this book. Here are 15 imaginative little pieces specially composed for the absolute beginner all of them with attractive piano accompaniments. The pieces are arranged progressively so you can hear the step-by-step improvement in your playing as well as simply enjoying the music.
Really Easy Trombone Book: Trombone: Instrumental Album
Gout Alan - Really Easy Trombone Book - Trombone And Piano 
Really Easy Trombone Book (With Piano)