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. 42, Waltz in A♭ major
GE1 added a cautionary 
next to a
even though Chopin had not written it into FEG. In GE2 (→GE3) the accidental was deemed unnecessary, an opinion we share. The same supplement to EE is most probably also a reviser's addition – flats occur in all analogous places (bars 21, 29, 37, 185, 193, 201 and 209), and this kind of thoroughness is beyond belief in case of Chopin (however, it cannot be ruled out that he added in e.g. only one of these bars).
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, GE revisions
notation: Pitch