Hodgetts, Richard M., author
Saunders, 1977
Buku Teks
Thill, John V., author
McGraw-Hill, 1991
Buku Teks
Westview Press, 1988
Buku Teks
Bryson, Bethany, author
Stanford University Press, 2005
Buku Teks
Bovee, Courtland L., author
Prentice-Hall, 2000
Buku Teks