Randall, Geoffrey
Routledge, 1993
Buku Teks
Kotler, Philip, author
Pearson, 2014
Buku Teks
Diamond, Jay, author
Prentice-Hall, 1986
Buku Teks
Kotler, Philip, author
Prenhallindo , 1997
Buku Teks
Lovelock, Christopher H., author
Pearson Education international, 2002
Buku Teks