Carpendale, Jeremy
Blackwell Publishing, 2006
Buku Teks
Lawson, Joseph W.R., II
American Management Association, 1998
eBooks
Modern Business Report , 1985
Buku Teks
Lorayne, Harry
Golden Books Centre SDN. BDN, 1992
Buku Teks
Baker, Sharon L.
Libraries Unlimited, 1993
Buku Teks