Green Brothers Advanced Instructor for Xylophone
The Green Brothers published this Advanced Instructor back in 1922. Its 87 pages includes photos and information that any percussionist will find helpful. There are exercises and etudes in several chapters: The Roll, Scales, Exercises in various time signatures and keys, Ornaments and Grace Notes, Arpeggios and Broken Chords, and several more.
While this is an advanced text, it is progressive in nature and would serve the intermediate player as well. The information and methodology presented in the Green Brothers Advanced Instructor never goes out of style. Check it out and see yourself.