Antique brass instrument on display at the Musical Instrument Museum in Brussels, Belgium This is a six-valved, seven-belled valve trombone by Adolf Sax. Each valve coincides with one position on a slide trombone.
Wind Talk for Brass: A Practical Guide to Understanding and Teaching Brass Instruments
Walter Beeler Method for the Trombone, Bk 1 (Walter Beeler Series for Brass Instruments)
Walter Beeler Method for the Cornet (Trumpet): Book 2 (Walter Beeler Series for Brass Instruments)