Goode, Roy
Penguin Books, 2004
Buku Teks
Macintryre, Ewan
Blackstone Press, 1998
Buku Referensi
Stephenson, Graham
Blakstone Press, 1995
Buku Teks
Bradgate, Robert
Butterworth, 1991
Buku Teks
Simpson, Laurence P.
Alexander Hamilton Institute, 1961
Buku Teks