Sylvia, Ronald D., author
Harcourt College Publisher, 2002
Buku Teks
Sylvia, Ronald D.
Harcourt College Publisher, 2002
Buku Teks
Cayer, N. Joseph, author
Thomson wadsworth, 2004
Buku Teks
Pfiffner, John M., author
Ronald Press, 1960
Buku Teks
edited by Robert T. Golembiewski, Frank Gibson, Geoffrey Y. Cornog
Rand McNally College, 1972
Buku Teks