Stephenson, Graham, author
Blakstone Press, 1995
Buku Teks
Goode, Roy, author
Penguin Books, 2004
Buku Teks
Bradgate, Robert, author
Butterworth, 1991
Buku Teks
Adams, Kristen David, author
St. Paul, MN : West Group, 2010
Buku Teks
Macintryre, Ewan, author
Blackstone Press, 1998
Buku Referensi