Hill, Napoleon
Jeremy P. Tarcher/Penguin, 2008
Buku Teks
Morris, Thomas
G.P. Putnam?s Sons, 1994.
Buku Teks SO
Pietrzak, Theodore
[American Society for Training and Development Press;;, ], 2005
eBooks
Hui, Xu
Pt Elek Media Kompuntindo, 1997
Buku Teks
Kunkel, Vicki
American Management Association, 2009
eBooks