Cook, Chris, author
Longman, 1991
Buku Referensi
Cook, Chris, author
Routledge, 2005
Buku Teks
Palmer, R.R. (Robert Roswell), 1909-2002, author
McGraw-Hill, 1992
Buku Teks
edited by John R. Burr
Greenwood Press, 1980
Buku Referensi
McWilliams, Wayne C., author
Adamantine Press, 1990
Buku Teks