Johannsen, Hano
Crest Publishing House, 1999
Buku Referensi
Ho, Samuel K.
Crest publishing, 1999
Buku Referensi
Thorne, Kaye
Crest publishing, 1999
Buku Referensi
Estop, Tora
[American Society for Training and Development Press;, ], 2005
eBooks
Hon, David
John Wiley & Sons, 1980
Buku Teks