Gannon, Martin J.
Little, Brown & Co., 1982
Buku Teks
Keller, kotler
Pearson Education, Inc, 2006
Buku Teks
Kotler, Philip
[publisher not identified], [date of publication not identified]
Buku Teks
Kotler, Philip
Prentice-Hall, 2000
Buku Teks
Wilson, Mike
Gower Publishing, 1985
Buku Teks