Grosse Fugue in B flat major Op Grosse Fugue in B flat major Op.133 Grosse fuge in B-flat major, op.133 Great Fugue in B flat major,Op 'Gross Fuge' in B flat major op.134 Great fugue in B flat major op. 133 Prelude in A-flat major op Prelude in B-flat major op Prelude in G-flat major op Prelude in E-flat major, op