John Hartley [and others]
Rinehart and Winston, 1962
Buku Teks
Kirk, Ken, author
American Society for Training & Development, 2010
eBooks
Bogg, Daisy, author
McGraw-Hill, 2012
Buku Teks
O`Shea, Robert P., author
Harcourt Brace , 1996
Buku Teks
Claiborne, Robert, author
Time-Life Books, 1974
Buku Teks