Goode, Roy, author
Penguin Books, 2004
Buku Teks
Clark, Lawrence S.
McGraw-Hill, 1988.
Buku Teks
Adams, Kristen David, author
St. Paul, MN : West Group, 2010
Buku Teks
Macintryre, Ewan, author
Blackstone Press, 1998
Buku Referensi
Bradgate, Robert, author
Butterworth, 1991
Buku Teks