generate questions: Works published since 1857 have received alternative catalogue designations instead of opus numbers. The present standard musicological reference for Chopin's works is the Kobylańska Catalogue (usually represented by the initials 'KK'), named for its compiler, the Polish musicologist Krystyna Kobylańska.
The Kobylańska Catalogue was named for who? {sep_token} Pieces published after what year stopped receiving opus numbers? {sep_token} What have pieces published after 1857 been given rather than opus numbers? {sep_token} What is the current musicologist reference for Chopin's pieces? {sep_token} What is the shortened reference for the Kobylańska Catalogue? {sep_token} Who compiled the Kobylańska Catalogue? {sep_token}