Musical variations from a chaotic mapping: Variation 3 (incorporating the BACH motif)
BACH motif. A transposition (C,B,D,C--sharp) of the notes B-flat,A,C,B-natural - the musical spelling of Bach’s name - appear in the soprano voice of mm. 28 and 29. The retrograde of the BACH motif occurs in mm. 12-15 of both Variation 3 and the original Prelude.
Source: Musical variations from a chaotic mapping [PDF]