http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Selective music lists: vocal solos, vocal ensembles
Music Educators National Conference (U.S.)
Society for the Preservation and Encouragement of Barber Shop Quartet Singing in America
Compiled cooperatively by the Music Educators National Conference and American Choral Directors Association, Society for the Preservation and Encouragement of Barber Shop Quartet Singing in America.