Venema, Adriaan
De Prom, 1990
Buku Teks
Kevin R. Cox and Reginald G. Golledge, editors
Routledge, 2016
Buku Teks
Osgood, Robert Endicott
Westview Press, 1979
Buku Teks
Hodell, Chuck
American Society for Training & Development, 2010
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