Colin-Jones, Graham
Times Books International, 1995
Buku Teks
Rosady Ruslan
RajaGrafindo Persada, 1999
Buku Teks
Arthur, Diane
American Management Association, 1997
eBooks
Schumacher, Michael
Writer's Digest Books, 1990
Buku Teks
O`Hair, Dan
Allyn and Bacon, 2011
Buku Teks