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. 4), Sonata in C minor
(Op. 4), Sonata in C minor, Mvt I
In A one can see that the 
to a
was being removed. Chopin entered it probably under the influence of the preceding bars, in which he had to write flats to the a1 notes.
Compare the passage in the sources »
category imprint: Corrections & alterations; Source & stylistic information
issues: Corrections in A, Last key signature sign
notation: Pitch