Haley, Charles W., author
McGraw-Hill, 1979
Buku Teks
Haley, Charles W., author
McGraw-Hill, 1973
Buku Teks
Rasmussen, Nils, author
Wiley, 2002
Buku Teks
Manser, W.A.P.
Cassell/Associated Business Programmes, 1973
Buku Teks
Vause, R.
McMillan Press , 1975
Buku Teks