Rich, Dorothy
Houghton Mifflin, 1992
Buku Teks
Paulus Winarno, author
Gramedia, 2005
Buku Teks
Zabel, William D.
William Morrow and Company, Inc., 1995
Buku Teks
Johnson, Winslow, author
[American Management Association, ], 2004
eBooks
Sternberg, Robert J., author
APA, 2000
Buku Teks