Kaplin, William A.
Jossey-Bass Publishers, 1980
Buku Teks
Ziegenfuss, James T.
Van Nostrand Reinhold Company, 1985
Buku Teks
Willborn, Steven L.
The Michie Company, 1993
Buku Teks
Player, Macka
West Publishing, 1992
Buku Teks
Harper, Michael C
Little, Brown and Company, 1996
Buku Teks