In A, starting the slur from bar 17 is most probably an inaccuracy, being a result of the transition to a new page. It was corrected in GE (→FE→EE); the traces of correction in print are clearly visible. At the same time, one can see that the slur in GE1 originally encompassed bars 17-19, which was changed to a slurring that was not only compliant with A, but also correcting the inaccuracy of the manuscript. In this case, the authenticity of this correction is unquestionable.
Compare the passage in the sources »
category imprint: Differences between sources; Corrections & alterations
issues: Authentic corrections of GE, Corrected slurs of Op. 21 in GE1
notation: Slurs
