Kelly, Gary F.
The Dushkin Publishing Group, 1992
Buku Teks
Damisch, Hubert
MIT Press, 2000
Buku Teks
Sarabjot Singh
Management, Faculty of Economics, University of Indonesia and Philip Kotler Center, 2013
Artikel Jurnal
Ruzaimi Mat Rani
Words & Visuals Press Pte Ltd,
Buku Referensi
Elkins, James
Cornell University Press, 1994
Buku Teks