Wells, William D.
John Wiley & Sons, 1996
Buku Teks
Schiffman, Leon G.
Pearson Education International, 2004
Buku Teks
Engel, James F.
Chicago Dryden Press, 1990
Buku Teks
Mowen, John C.
Macmillan, 1987
Buku Teks
Schiffman, Leon G.
Prentice-Hall, 1997
Buku Teks