The meaning of the entry in bar 66 is unclear, although most probably it concerns simultaneous performance of the e
1-g1 third with the 1st finger of the L.H. (the grip was marked by Chopin on a number of occasions, e.g., in the Piano Concerto in E minor, Op. 2, 2nd mov., bar 16 or the Prelude in A major, Op. 28 No. 7, bar 12). Another possibility is the use of 1st fingers of both hands, which was indicated by Fontana in EE.
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category imprint: Differences between sources
issues: Annotations in teaching copies, EE revisions, Annotations in FED
notation: Fingering