Thorn, Eric A.
Jay Books , 1989
Buku Teks
Strong, William S.
MIT Press, 1981
Buku Teks
Akester, Patricia
Sweet & Maxwell, 2008
Buku Referensi
Akester, Patricia
Sweet & Maxwel, [Date of publication not identified]
Buku Teks
Harris, Lesley Ellen
American Management Association, 2009
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