Czinkota, Michael R.
Dryden Press, 1996
Buku Teks
Wild, John J.
Prentice-Hall, 2003
Buku Teks
Czinkota, Michael R.
Dryden Press, 1994
Buku Teks
Mason, R. Hal (Robert Hal), 1929-
John Wiley & Sons, 1981
Buku Teks
Wild, John J.
Prentice-Hall International, 2001
Buku Teks