Puxon, Margaret
Penguin Books, 1971
Buku Teks
Pace, P.J.
Pitman, 1992
Buku Teks
Seng, Kenneth Wee Kim
University of Singapore, 1976
Buku Teks
O`rourke, Raymond
Palladian law Publishing Ltd., 1998
Buku Teks
Cuthbert, Mike
Cavendish Publishing Limited, 1993
Buku Teks