Treatise of Harmony – Bass and Voices is an absolute must-have volume on harmonies by Théodore Dubois. Written in the last century (1921) this book includes the two parts of the treatise: Part 1 – Basses and Part 2 – Voices. This volume is quite complex requires some strong theory knowledge and would be playable by upper-advanced players and professionals. It also features numerous examples. The two parts contains the following sub-sections: Part 1 – Basses: - Consonant harmonies - Dissonant harmonies - Alterations - Delays - Pedals - Appendix Part 2 – Voices: - Consonant harmonies - Dissonant harmonies - Alterations - Delays Pedals… - Appendix