Symphony, K. 75 (Mozart) works from this time period, such as the K. 97 symphony, the autograph, which was in the possession of Breitkopf & Härtel, was destroyed during World War II. Mozart's authorship therefore remains uncertain. Most professionals consider the work authentic. The Alte Mozart-Ausgabe (published 1879–82) gives the numbering sequence 1–41 for the 41 numbered symphonies. The unnumbered symphonies (some, including K. 75, published in supplements to the Alte-Mozart Ausgabe until 1910) are sometimes given numbers in the range 42 to 56, even though they were written earlier than Mozart's Symphony No. 41 (written in 1788). The symphony K. 75 is given
Catalogues of Beethoven compositions catalogue in the 1950s, in which he included pieces not included in the 19th century complete edition published by Breitkopf and Härtel. Hess included many more fragmentary works than did Kinsky, and his catalog runs to 335 entries in the "Hauptkatalog" (main catalogue), and 66 "doubtful and falsely-attributed" works in an appendix. Many pieces have both WoO and H numbers. Beethoven's compositions are also organized through the Biamonti Catalogue, compiled by Giovanni Biamonti and published in 1968. This work is an attempt to chronologically order all of Beethoven's creative output, in a manner similar to the catalogue of Franz Schubert's