Dizard, Wilson, Jr., author
Praeger, 2001
Buku Teks
Mattingly, Garrett, author
Houghton Miffiln, 1955
Buku Teks
Langley, Billy C.
Reston Publishing Co., 1983
Buku Teks
Hughes, Edward, author
Longmans, 1970
Buku Teks
Hughes, Gerard J.
Routledge, 1995
Buku Teks