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
Stocker, H. E.
Prentice-Hall, 1938
Buku Teks
Howell, Edward Beach
Amacom , 1996
Buku Teks