Bach's The Art of the Fugue, BWV 1080

Manuscript (p. 1) in the Berlin State Library

First Edition of 1751 (p. 1 and pages with art) edited by C.P.E. Bach

Breitkopf und Härtel (1926) — 6 staves for most of the fugues: soprano clef, alto clef, tenor clef, bass clef, and piano reduction

Creative Commons (2018) — 4 staves for most of the fugues using modern clefs

Britannica article