Brannan, Tom, author
Crest Publishing House, 2001
Buku Teks
Keegan, Warren J., author
Pearson , 2013
Buku Teks
Czinkota, Michael R., author
The Dryden Press, 1996
Buku Teks
Fitzpatrick, Peter B., author
AMA Membership Publications Division, American Management Association, 1985
Buku Teks
Cundiff, Edward W., author
Prentice-Hall, 1988
Buku Teks