Lucas, Bill, author
Nicholas Brealey Publishing, 2002
Buku Teks
Wallace, Harold R.
South-Western Educational, 1995
Buku Teks
Addison Wesley Publishing Company, 0
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Strommen, Ellen A., author
Dorsey Press, 1983
Buku Teks
Lykins, Lorrie, author
American Society for Training & Development, 2011
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