Atkinson, Brian, author
Addison - Wesley , 1998
Buku Teks
Czinkota, Michael R., author
The Dryden Press , 1996
Buku Teks
Jucius, Michael J., author
Richard D. Irwin, 1961
Buku Teks
Gerstenberg, Charles W., author
Prentice-Hall, 1918
Buku Teks
Hastings, Paul G., author
McGraw-Hill, 1974
Buku Teks