Hyland, Bruce
Gramedia Pustka Utama, 1996
Buku Teks
Harvard Business School Press, 2004
Buku Teks
Flagello, Jane R.
American Management Association, 2009
eBooks
Haneberg, Lisa
American Society for Training & Development, 2007
eBooks
Crittendon, Robert
[American Management Association;, ], 2002
eBooks