Piano Pentascales & Chords: Easy to read - visual format

ChordTime Piano Christmas Level 2B. (Chordtime Piano, Level 2b, I-iv-v7 Chords in Keys of C, G and F)

Essential Piano Exercises Every Piano Player Should Know: Learn Intervals, Pentascales, Tetrachords, Scales (major and minor), Chords (triads, sus, ... Piano Player Should Know by Jerald Simon)

Piano Chord Songbook.

Piano Chord Basics