Maxey, Cindy, author
American Society for Training & Development, 2007
eBooks
O`Neil, John R., author
McGraw-Hill, 1995
Buku Teks
Huffington, Arianna, author
Harmony Books, 2015
Buku Teks
Hill, Napoleon, author
Jeremy P. Tarcher/Penguin, 2008
Buku Teks
Morris, Thomas
G.P. Putnam?s Sons, 1994.
Buku Teks