Bowie, Fiona, author
BlackWell Publishing, 2005
Buku Teks
Firth, Raymond, author
Routledge, 1996
Buku Teks
Johnstone, Ronald L., author
Prentice-Hall, 1975
Buku Teks
edited by Peter Clarke and Stewart Sutherland
Routledge, 1991
Buku Teks
Bowen, John R., author
Pearson, 2005
Buku Teks