Answered By: Information Commons
Last Updated: Jul 01, 2014     Views: 85

Some composers' musical works are identified by opus numbers. Publishers often assign these numbers to a given composer's works by order of their composition or order of their publication. The usual abbreviation is "Op.". Occasionally, one also may see the designation, "WoO," which stands for "Werk ohne Opus" or "work without an opus number" or "Op. posth." which means "opus posthumus" or a work published after the composer's death.

For example:

  • Berlioz's Les nuits d'été, Op. 7
 When searching for the score or recording of this piece, simple use the keyword search field in WorldCat Discovery and type a search such as "berlioz and nuits d'ete and op. 7", choose the format you want from the pulldown menu such as score or sound recording, and hit enter or click on "search".  WorldCat Discovery searches are not case sensitive.