West Publishing Co, 1987
Buku Teks
Mandelker, Daniel R., author
Michie Company, 1985
Buku Teks
Hales, Michael G.
Prentice-Hall, 1989.
Buku Teks
Crilly, William M., author
American Management Association;, 2010
eBooks
Praeger Publishers, 1976
Buku Teks