Parten, Mildred
Haper & Brother, 1950
Buku Teks
Vaus, D.A.de
University College London Press, 1996
Buku Teks
Sabine Hader, Michael Hader, Mike Kuhne, editors
[Springer, Springer], 2012
eBooks
Conway, Mal, author
American Society for Training & Development Press, 2003
eBooks
World Health Organization
World Health Organization, 2013
Buku Teks