Goode, Roy, author
Penguin Books, 2004
Buku Teks
Macintryre, Ewan, author
Blackstone Press, 1998
Buku Referensi
Bradgate, Robert, author
Butterworth, 1991
Buku Teks
Stephenson, Graham
Blakstone Press Limited, 1995
Buku Teks
Ryder, Nicholas, author
Cambridge University Press , 2012
Buku Teks