Hill, Napoleon, author
Jeremy P. Tarcher/Penguin, 2008
Buku Teks
Morris, Thomas
G.P. Putnam?s Sons, 1994.
Buku Teks
Bono, Edward de, author
Fontana, 1991
Buku Teks
Pietrzak, Theodore, author
[American Society for Training and Development Press;;, ], 2005
eBooks
Hui, Xu, author
Pt Elek Media Kompuntindo, 1997
Buku Teks