Griffin, Ricky W.
Prentice-Hall, 1999
Buku Teks
Griffin, Ricky W.
Prentice-Hall, 2002
Buku Teks
Wheeler, Bayard O.
Harper & Row. Publisher, 1968
Buku Teks
Atkinson, Brian
Addison - Wesley , 1998
Buku Teks
Czinkota, Michael R.
The Dryden Press , 1996
Buku Teks