Bruce, R. Robert, author
Hodder & Stoughton, 1994
Buku Teks
Tong, Keith S. T., author
Routledge, 1994
Buku Teks
Coggle, Paul, author
Teach Youeself Books, 1991
Buku Teks
Bhatia, Tej K., author
Routledge, 2000
Buku Teks
Coultas, Barbara, author
Teach Yourself Books, 1990
Buku Teks