Hamper, Robert J.,
NTC Bussiness Book, 1992
Buku Teks
Chisnall, Peter M
Prentice-Hall, 1989
Buku Teks
Battersby, Albert, author
Penguin Books, 1968
Buku Teks
Cespedes, Frank V.
Harvard Business School Press, 1995
Buku Teks
Kerin, Roger A., author
Allyn and Bacon, 1990
Buku Teks