Ashley, Kevin D.
Mass. MIT Press , 1990
Buku Teks
Kirchheimer, Otto
Princeton University press, 1961
Buku Teks
Ward, Francine
American Society for Training & Development, 2007
eBooks
edited by Elizabeth M. Moys
Westview Press, 1976
Buku Teks
Warnick, Barbara, 1946-
Macmillan, 1994
Buku Teks