Hutchinson, John, author
Sage Publications, 2005
Buku Teks
Pickering, Peg, author
Erlangga, 2001
Buku Teks
Rex, John
Oxford University Press, 1979
Buku Teks
edited by Jiri Valenta, Esperanza Duran
Allen & Unwin, 1987
Buku Teks
Jeong, How-Won, author
Ashgate, 2000
Buku Teks