In a number of cases, more than one catalogue exists, or has existed, for the same composer's works. In most such cases, only one will be considered the current standard catalogue for the purposes of musicological indexing. For example,
Liszt's works are now known only by S numbers, from the catalogue by
Humphrey Searle, which superseded that created by
Peter Raabe, which used R numbers. Older catalogues are included for
historiographic purposes. But there are exceptions to this, such as: • For
Domenico Scarlatti, the
Longo catalogue (
L numbers) was in use from 1906, and although it has become generally superseded by the 1953
Kirkpatrick catalogue (
K or
Kk numbers), L numbers are still seen in references. In 1967,
Pestelli created a third catalogue (
P numbers), which has found acceptance in some places. Because all three symbols are often encountered, there is a
concordance to help navigate between them. •
Beethoven's works can appear with an opus number, a WoO number, a Hess number or a Bia number (see
Catalogues of Beethoven compositions). Until 1955, the opus numbers that appeared in the
Beethoven Gesamtausgabe were used exclusively, but this edition omitted a large number of works. In 1955, Georg Kinsky and Hans Helm produced a listing of works that had not been given opus numbers, and gave them
WoO numbers (
Werke ohne Opuszahl, or "Works without opus number"). This listing is often referred to as the Kinsky Catalogue. In 1957,
Willy Hess produced a new catalogue of Beethoven's unpublished works, which included all or most of the Kinsky Catalogue as well as other pieces; Hess numbers were allocated to this sequence of works. In 1968, Giovanni Biamonti produced the
Biamonti Catalogue, which sought to combine and update all pre-existing catalogues. Bia numbers relate to this catalogue. • Note: The WoO symbol has also been used to classify some other composers' works that were not given opus numbers, such as certain works by
Mendelssohn,
Schumann and
Brahms. • In
Chopin's case, at least four latter-day catalogues vie for prominence:
Maurice J. E. Brown (
B numbers);
Krystyna Kobylańska (
KK numbers);
Józef Michał Chomiński, whose catalogue is segmented into six parts, each part utilising a different letter (
A, C, D, E, P and
S); and
Chopin National Edition WN numbers. Hence, a work of Chopin can be referred to by its opus number and/or a catalogue number preceded by one of nine letter symbols. • The cataloguing of
Bartók's works is similarly complex. Bartók assigned opus numbers to his works three times. He ended this practice with the Violin Sonata No. 1, Op. 21 in 1921, because of the difficulty of distinguishing between original works and ethnographic arrangements, and between major and minor works. Since his death, three attempts—two full and one partial—have been made at cataloguing. The first, and still most widely used, is
András Szőllősy's chronological
Sz numbers, from 1 to 121.
Denijs Dille subsequently reorganised the juvenilia (Sz. 1–25) thematically, as
DD numbers 1 to 77. The most recent catalogue is that of
László Somfai; this is a chronological index with works identified by
BB numbers 1 to 129, incorporating corrections based on the Béla Bartók Thematic Catalogue. ==Ordinary usage==