Fogg, C. Davis
AMACOM, American Management Association, 1994
Buku Teks
Wheelan, Susan A.
Sage, 1999
Buku Teks
Cleland, David I., author
John Wiley & Sons, 1996
Buku Teks
Thompson, Leigh L., author
Pearson - Prentice Hall, 2008
Buku Teks
Charron, C. G.
Macmillan, 1976
Buku Teks