Fryar, Maridell
National Textbook Co., 1979
Buku Teks SO
Kruger, Arthur N.
The Scarecrow Press, Inc., 1968
Buku Teks SO
Jacobson, Michael D.
Routledge, 1987
Buku Teks SO
Fedrizzi, Mariann
South Western Cengage Learning, 2011
Buku Teks SO
Vancil, David L.
Allyn and Bacon, 1993
Buku Teks