The Buzzing Book - a complete method by James Thompson. Comes complete with 2 CD's (one in Bb and one in C) with accompaniments to the exercises. The method covers everything you need to know about buzzing and although the exercises work well with just a mouthpiece the use of a BERP is recommended. The primary objective is to encourage the use of more air and develop better control - side benefits include better range, endurance and flexibility.