Symphony, K. 45b (Mozart) even earlier dates to also be possible, and Zaslaw dated the symphony cautiously to Salzburg in 1767. Einstein also believed that the symphonies in the catalogue of Breitkopf & Härtel were sent by Leopold Mozart to be published. The Alte Mozart-Ausgabe (published 1879–1882) gives the numbering sequence 1–41 for the 41 numbered symphonies. The unnumbered symphonies (some, including K. 45b, 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. 45b is given the
Catalogues of Beethoven compositions and Hans Halm published a catalogue of Beethoven's works, in which they assigned numbers to 205 "Werke ohne Opuszahl" (meaning "works without opus number" in German) to "some" of Beethoven's unpublished works. These numbers given these works are generally preceded by "WoO". The Kinsky–Halm catalogue also lists 18 works in an appendix as being either doubtfully attributed, or simply spurious. Some of those listed as doubtful have since been shown to be authored by Beethoven. These numbers are generally preceded by "Anh.", short for German "Anhang", meaning "appendix". The Swiss composer and musicologist Willy Hess also researched and published a