The three augmented-sixth chords, under the nationalities convention gives them.
Over an Ab bass in C: the Italian sixth is Ab C F#, the French sixth adds the supertonic (Ab C D F#), and the German sixth adds the lowered mediant (Ab C Eb F#).
The three augmented-sixth chords, under the nationalities convention gives them.
Over an Ab bass in C: the Italian sixth is Ab C F#, the French sixth adds the supertonic (Ab C D F#), and the German sixth adds the lowered mediant (Ab C Eb F#).