Frequently, songs that are included in anthologies are not listed individually in the online catalog and therefore are not findable using either keyword or title searches (see, for instance, The Beatles: The Complete Scores). Song indexes include lists of songs - sometimes arranged by song title, sometimes arranged by composer, sometimes both - and provide cross-references for the anthologies that include each song.
To identify songs in collections, start with the song indexes listed here. Look up the song by title, composer, first line, or whatever information you have. There will be some sort of code that represents the anthology (or anthologies) that contain that song: look in the front of the index for a key that will tell you which anthology corresponds to which code. When a collection containing the desired song is identified, search the KU Libraries Catalog by the anthology title to determine if KU owns the collection. Don't despair if we do not! Return to the song indexes and search further, or place a request through Interlibrary Loan.