박재성 저, [통합음악이론] 제14장 (Part 1)(증6화음, 완전5도/단6도/장6도/증6도) (Augmented 6th Chords, Perfect 5th / Minor 6th / Major 6th / Augmented 6th). 이탤리6화음, 프랑스6화음, 독일6화음.