Crego, Edwin T., author
[American Management Association;, ], 1995
eBooks
Westwood, John, author
Gramedia, 2006
Buku Teks
Murray, Rowena
Open University Press, 2002
Buku Teks
Vallins, G.H.
Andrew Deutsch, 1952
Buku Teks
Reader's Digest Service, 1987
Buku Teks