Ferrell, O.C., author
Thomson South-Western, 2008
Buku Teks
Boyd, Harper W., Jr., author
Richard D. Irwin, 1958
Buku Teks
Kelley, Eugene J.
Prentice-Hall, 1965
Buku Teks
Thorelli, H.B., author
Penguin Books, 1973
Buku Teks
edited by Philip Kotler, Keith K. Cox
Prentice-Hall, 1984
Buku Teks