Smith, Christopher E.
Nelson-Hall Publishers, 1992
Buku Teks
Perry, Michael J.
Oxford University Press, 1997
Buku Teks
Sellin, J. Thorsten
Elsevier, 1976
Buku Teks
Washington, Booker T., author
Oxford University Press, 1900
Buku Teks
Barry, Kathleen
Prentice-Hall, 1979
Buku Teks