Content and organization of a Collected Works edition may be found through the following:

• A contents note in the online catalog or card catalog or in WorldCat
  •  Examples:
  •              In the Online Catalog:Beethoven Collected Works.
  • The WorldCat link is also found through the Music Library homepage:

Carl Philipp Bach The complete Works                        Beethoven Werke 1864

• Examine the physical volumes of the edition as they may include a contents note for the entire edition in each volume  
  • Example:"CPE Bach Collected Works Introduction"  Not always, but often, an examination of the spines of volumes in each edition may also give you an idea of its organization.

• Scholarly websites of societies devoted to the works of a composer or devoted to a Collected Works edition of the composer can offer useful information, but use caution and verify information on your own. Sites might be incorrect if out-of-date. Do a title search or check Wikipedia articles for "External links" to quickly find the URLs of composer societies. Example: C.P.E. Bach (incorrect)  C.P.E. Bach

• If the edition existed before 1980 this reference work will give you a view of its organization:
  • Example: Heyer Beethoven Example

Historical sets, collected editions, and monuments of music : a guide to their contents.
(1980)