Complex sentence: Thematisch-bibliographisches Werkverzeichnis (known as "Kobylańska Katalog" or KK), a complete and definitive thematic catalogue of all the musical works by Frédéric Chopin.
Split into simpler sentences: Thematisch-bibliographisches Werkverzeichnis (known as "Kobylańska Katalog" or KK). It is a complete (and definitive) thematic catalogue of all the works by Frédéric Chopin.