edited by John D. Montgomery, William J. Siffin
McGraw-Hill, 1966
Buku Teks SO
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
Simon, Herbert A., author
Alfred A. Knopf, 1973
Buku Teks
Denhardt, Robert B., author
Harcourt College, 1999
Buku Teks