Downes, T. Antony
Blackstone Press, 1993
Buku Teks
Downes, T. Antony
Black Stone Press, 1997
Buku Teks
Williams, Katherine S.
Blackstone Press, 1997
Buku Teks
Houston, William John Ballantyne
Butterworth-Heinemann, 1992
Buku Teks SO
Jones, Michael A.
Blackstone Press Limited, 2000
Buku Referensi