Drewniany, Bonnie L.
Wadsworth, Cengage Learning, 2014
Buku Teks
Clarke, George Timothy
New York University, 1959
Buku Teks
Lewis, Herschell Gordon
Prentice-Hall, 1988
Buku Teks
edited by George Zinkhan
American Marketing Association, 2000
Buku Teks
Trout, Jack
McGraw-Hill, 1996
Buku Teks