Grout, Jeff
McGraw-Hill Companies, 2002
Buku Teks
Gay, Charles L., author
Nicholas Brealey Pub, 2000
Buku Teks
Brantley, Mary Ellen., author
McGraw-Hill , 2001
Buku Teks
Kevin Oakes and Pat Galagan, editors
American Society for Training & Development, 2011
eBooks
O`Leary, John, author
QS Quacquarelli Symonds Limited, 2010
Buku Referensi