Paulus Winarno
Gramedia, 2005
Buku Teks
Zabel, William D.
William Morrow and Company, Inc., 1995
Buku Teks
Johnson, Winslow
[American Management Association, ], 2004
eBooks
Sternberg, Robert J.
APA, 2000
Buku Teks
Zweig, Jason
Simon & Schuster, 2007
Buku Teks