Attwood, Gaynor, author
McGraw-Hill, 1989
Buku Referensi
Gunton, Tony, author
Penguin Books, 1993
Buku Referensi
Meadows, A.J., author
Kogan Page, 1982
Buku Referensi
Longley, Dennis, author
Macmillan, 1982
Buku Referensi
Gunton, Tony, author
NCC Blackwell, 1993
Buku Teks