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