Goode, Roy
Penguin Books, 2004
Buku Teks
Bradgate, Robert
Butterworth, 1991
Buku Teks
Macintryre, Ewan
Blackstone Press, 1998
Buku Referensi
Adams, Kristen David
St. Paul, MN : West Group, 2010
Buku Teks SO
Simpson, Laurence P.
Alexander Hamilton Institute, 1961
Buku Teks