Reed, Susan E.
Amacom, 2011
Buku Teks
Hira, Ron
American Management Association, 2008
eBooks
Hayles, V. Robert
McGraw-Hill , 1997
Buku Teks
Farrell, Warren
[American Management Association, ], 2005
eBooks
Seligman, Eustace
New York University Press, 1956.
Buku Teks