Mill, Robert Christie, author
RajaGrafindo Persada, 2000
Buku Teks
Czinkota, Michael R., author
The Dryden Press, 1994
Buku Teks
Mason, R. Hal (Robert Hal), 1929-, author
John Wiley & Sons, 1981
Buku Teks
Wild, John J., author
Prentice Hall International, 2001
Buku Teks
Czinkota, Michael R., author
The Dryden Press, 1992
Buku Teks