Shinn, George
Gregg Division, McGraw-Hill, 1982
Buku Teks
Manning, Gerald L., author
Prentice Hall International, 1998
Buku Teks
Williams, Alan
McGraw-Hill, 1983
Buku Teks
Johnson, Spencer, author
Harper Collins, 2004
Buku Teks
Gamble, Teri Kwal, author
American Society for Training & Development, 2007
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