Laurel, Deborah Spring
American Society for Training & Development, 2008
eBooks
Maxwell, John C.
NY : Center Street, 2014
Buku Teks
Heng, Paul
Prentice-Hall, 2001
Buku Teks
Wee, Heng Neo
Pearson Prentice Hall, 2004
Buku Teks
Entrepreneur Press Rich Mintzer
Entepreneur Press, 2011
Buku Teks