The Public Domain Song Anthology (Online) by Oxford Online Bibliographies compile authoritatively selected and annotated citations for key reference works, collected correspondence, biographies, monographs, and articles relating to prominent composers.
Research guides provide detailed listings for a composer's known musical and literary works followed by annotated bibliographies of the secondary literature on the composer's œuvre arranged by genre and important topics in the composer's life, career, and reception history—plus other features such as a genealogies, chronologies, and indexes.
Companions collate major essays by established experts that address key aspects of the composer's career, creative work, style, and critical reception.
