in 
All dynamic markings given in the main text in bars 19-25 were added by Chopin in one of the later proofreadings of FE (→GE,EE). The composer introduced the changes in a relatively complete and correct text of the Etude, which may be considered as a positive factor – a sui generis warranty of an already balanced and mature concept. On the other hand, Chopin could have felt embarrassed by introducing another abundant portion of additions to an already meticulously corrected text, not to mention the urgent deadline (cf. the characteristics of FEcor). In this situation we believe that the much more detailed indications of Ap – despite its obvious authenticity – may be considered as an addition to the indications of FE only with considerable caution. In case of some indications and signs in Ap (e.g. 
in bars 20, 22 and 24), juxtaposing them with the indications of FE is simply impossible.
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category imprint: Differences between sources
issues: Authentic corrections of FE
notation: Verbal indications