Prelude in A flat major, BWV 862 Prelude in B flat major, BWV 890 Prelude in E flat major,BWV 876 Prelude in A flat major, op. posth Prelude in A flat major,op.post. Prelude in A flat major,op.posth Prelude in E-flat major, op Prelude in A flat major, op.posth. Prelude in D flat major, op.28 no.15 No. 17 in A flat major, BWV 862