Smallbone, Douglas
Staples Press, 1971
Buku Teks
Liff, Stewart, author
American Management Association, 2007
eBooks
editor, Cat Sharpe
[American Society for Training and Development Press, American Society for Training and Development Press], 2000
eBooks
Dowling, William F., author
McGraw-Hill Kogakusha, 1978
Buku Teks
McQuaiq, Jack H
Frederick Fell. Inc, 1973
Buku Teks