Wilson, Arthur, author
London: Longman, 1968
Buku Teks
Hall, Oakley
Story Press, 1989
Buku Teks
editor by. Shahrudin Mohd Nor
ISI , 1996
Buku Referensi
Benson, Tedd, author
CT Taunton Press, 1999
Buku Teks
Coleman, Tina, author
[American Management Association, ], 2009
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