Treatise of Harmony – Bass and Voices is an absolute must-have volume on harmonies by Thédore 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...