Hui, Xu, author
Pt Elek Media Kompuntindo, 1997
Buku Teks
Asiapac Books, 2002
Buku Teks
Hill, Napoleon, author
Jeremy P. Tarcher/Penguin, 2008
Buku Teks
Langford, Beverly Y., author
American Management Association, 2005
eBooks
Morris, Thomas
G.P. Putnam?s Sons, 1994.
Buku Teks