Free public domain sheet music from IMSLP / Petrucci Music Library
PDF scanned by Unknown
Leipzig: C.F.W. Siegel, n.d.. Plate 6027-6028.
Public Domain [tag/del]
Color scan. At first only 9 were planned, as can be seen from the plan on the front cover which lists 3 books (plates 6027-29) of 3 each. Later references list 18, so the plan was later expanded.
||18 Preludes and Fugues for Piano, Op.56
||Frau Louise Härtel