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. 23, Ballade in G minor
FE (→GE,EE) added an unobvious cautionary 
to a in the 2nd crotchet. It suggests that it was Chopin who performed it, since a few other situations prove the composer's subconscious uncertainty as to the validity of a 3rd key signature 
, e.g. the mistake in b. 231.
Compare the passage in the sources »
category imprint: Differences between sources
issues: Cautionary accidentals, Authentic corrections of FE
notation: Pitch