Low, W. Augustus, and Virgil A. Clift, eds. Encyclopedia of Black America . Miller, Randall M., and John David Smith, eds. Dictionary of Afro-American Slavery . A comprehensive reference work on slavery in the United States.
Entries have bibliographies.
A good place for the beginning researcher. Facts About Blacks . Also covers other subject areas. Horton, Carrell Peterson, and Jessie Carney Smith, comps. and eds. Statistical Record of Black America .