Gilmer, B. von Haller (Beverly von Haller), 1909-1994, author
McGraw-Hill, 1967
Buku Teks
Maxwell, John C., author
MIC , 2016
Buku Teks
Duffy, Karen G., author
Pearson Education, Inc., 2005
Buku Teks
Duffy, Karen G., author
New Jersey, 2005
Buku Teks
Smith, Jim, author
American Society for Training & Development, 2008
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