In A (→GE1) there is a cautionary 
before g flat1 at the beginning of bar 16. The unnecessary sign was omitted in FE (-→EE1→EE2), and in GE2 (→GE3) it was moved one quaver earlier, to bar 15. In EE3, a was added in bar 16, probably on the basis of GE1.
Compare the passage in the sources »
category imprint: Differences between sources
issues: GE revisions, Cautionary accidentals, Authentic corrections of FE, Last key signature sign
notation: Pitch