Thematic catalogs enumerate and describe known works of composers and usually include information on manuscript locations, first publication, and first performance. Thematic catalogs can be found under the call number ML134, sub-arranged alphabetically by composer. Also in the ML134’s are bibliographies (guides to other writings) about the composers and their music.
Use thematic catalogs to verify the existence of a musical work, its title, opus number, instrumentation, etc. Thematic catalogs generally give information on the location of surviving manuscripts, sketches, or early printed editions. They also cite secondary literature regarding the work, many times this is literature that pre-dates the coverage of the standard music literature indexes.