Euphonium Guide is a real method for working this musical instrument (long tones, mouthpiece buzzing, lip slurs, tonguing and scales). It allows the user to record exercises while working to ensure its intonation and his tone homogeneity.
Regular practice using these application will provide an excellent basis for tackling difficult passages in the euphonium repertoire. This application also contains a tuning fork (Bb2, 440), advice to how work on each lesson and a bibliography on the euphonium/baritone.