Pelton, Lou E., author
McGraw-Hill Irwin, 2002
Buku Teks
Anne T. Coughlan, Eric Anderson, Louis W. Stern, Adel El-Ansary
Prentice-Hall, 2001
Buku Teks
Rosenbloom, Bert, author
South Western Cengage Learning, 2012
Buku Teks
Stern, Louis W.
Prentice Hall Inc., 1982
Buku Teks
Varey, Richard J., author
John Wiley & Sons, 2002
Buku Teks