Todd, Paul, author
London : Balckstone, 1994,
Buku Referensi
Todd, Paul
London Blackstone 1996.,
Buku Referensi
Heydon, J.D.
Butterworth, 1993
Buku Teks
Hudson, Alastair, author
Cavendish Publishing Limited, 2003
Buku Teks
Pettit, Philip H.
English Language Book Society , 1985
Buku Teks