Crimp, Margaret, author
Prentice-Hall, 1995
Buku Teks
Zikmund, William G., author
South Western Cengage Learning, 2013
Buku Teks
Churchill, Gilbert A., author
The Dryden Press, 1995
Buku Teks
edited by Joseph Seibert & Gorden [i.e. Gordon] Wills
Penguin Books, 1970
Buku Referensi
Zikmund, William G., author
South-Western, Cengage Learning, 2010
Buku Teks