Naxos Music Library This link opens in a new windowNaxos Music Library [NML] is the world´s largest online classical music library. New CDs are added to the library every month. The library offers the complete Naxos and Marco Polo catalogues plus the complete catalogues or selected titles from over 650 record labels. Music in this library may be used for class sessions, but when it comes to public performances, an individual license will need to be purchased.