Mark, Margaret
McGraw-Hill , 2001
Buku Teks
Ford, J. Kevin
John Wiley & Sons, 2005
Buku Teks
Post, Karen
[American Management Association, ], 2004
eBooks
edited by Debbie Millman
Rockport Publishers, 2012
Buku Referensi
Trout, Jack
Erlangga, 2001
Buku Teks