Colin-Jones, Graham, author
Times Books International, 1989
Buku Teks
Colin-Jones, Graham, author
Times Books International, 1995
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Rosady Ruslan, author
RajaGrafindo Persada, 1999
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Arthur, Diane, author
American Management Association, 1997
eBooks
Schumacher, Michael, author
Writer's Digest Books, 1990
Buku Teks