Taffinder, Paul, author
Kogan Page, 2001
Buku Teks
Zenger, John H., author
McGraw-Hill, 2004
Buku Referensi
Mackoff, Barbara, author
American Management Association, 2001
Buku Teks
Zenger, John H., author
McGraw-Hill, 2003
Buku Teks
Olson, Christi A., author
[American Library association, American Library association], 2004
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