Altfest, Lewis J.
McGraw-Hill, 1992
Buku Teks
Vangundy, Arthur B., author
American Management Association, 2007
eBooks
Reed, David, author
American Management Association;, 2008
eBooks
Hurford, Daphne M
Scribner, 1998
Buku Teks
Reitman, Annabelle, author
American Society for Training & Development, 2006
eBooks