Vickers, Brian
at the University Press, 1968
Buku Teks
Gooch, G.P., author
Oxford University Press, 1946
Buku Teks
Suchman, Edward A., author
Russell Sage Foundation, 1967
Buku Teks
Thiessen, Frank J.
Reston Publishing, 1984
Buku Teks
Phillips, Patricia Pulliam, author
American Society for Training & Development, 2012
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