MacStravic, Robin E. Scott
Aspen Systems Corp., 1977
Buku Teks
Kotler, Philip
Prentice-Hall, 1987
Buku Teks
Baum, Neil
Jones & Bartlett Learning, 2010
Buku Teks
Hillestad, Steven G.
An Aspen Publication, 1991
Buku Teks
The Haworth Press, 1991
Buku Teks