Op. 2, Variations in B♭ major
Op. 10, 12 Etudes
Op. 11, Concerto in E minor
Op. 21, Concerto in F minor
Op. 22, Polonaise in E♭ major
Op. 24, 4 Mazurkas
Op. 25, 12 Etudes
Op. 26, 2 Polonaises
Op. 27, 2 Nocturnes
Op. 28, 24 Preludes
Op. 30, 4 Mazurkas
Op. 35, Sonata in B♭ minor
Op. 50, 3 Mazurkas
Op. 63, 3 Mazurkas
Op. 64, 3 Waltzes
Op. 21, Concerto in F minor, Mvt III
The c1-a1 sixth is most probably a mistake of the engraver of FE (→EE). It is difficult to assume that Chopin would like to replace the sequence of three voices of the accompaniment, compliant with all rules, with a parallel shift of chords, sounding worse.
Compare the passage in the sources »
category imprint: Differences between sources
issues: Errors in FE, Terzverschreibung error
notation: Pitch