Shapiro, Alan C., author
Allyn and Bacon, 1992
Buku Teks
Eitman, David K., author
Perason, 2001
Buku Teks
Manser, W.A.P.
Cassell/Associated Business Programmes, 1973
Buku Teks
Faguet, Dmitri, author
John Wiley & Sons, 2003
Buku Teks
Vause, R.
McMillan Press , 1975
Buku Teks