The sources differ in the placement of cautionary naturals before the notes a in those bars. FE has only one natural and just in bar 48 (before the 3rd quaver). The sign is also present in EE, in which, however, another three were added in bar 47 – before a2 in the chord at the beginning of the bar and two in the L.H. In GE 
were placed before the first appearance of the note in each hand; undoubtedly, the sign before the 4th quaver was added during the proofing.
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, GE revisions, Cautionary accidentals
notation: Pitch