Seekings, David, author
Crest publishing, 1999
Buku Referensi
Johannsen, Hano, author
Crest Publishing House, 1999
Buku Referensi
Ho, Samuel K., author
Crest publishing, 1999
Buku Referensi
Thorne, Kaye, author
Crest publishing, 1999
Buku Referensi
Estop, Tora, author
[American Society for Training and Development Press;, ], 2005
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