Heady, Ferrel
Prentice-Hall, 1966
Buku Teks
Heady, Ferrel
Marcel Dekker, 1991
Buku Teks
edited by Nimrod Raphaeli
Allyn and Bacon, 1967
Buku Teks
Pfiffner, John M.
Ronald Press, 1960
Buku Teks
edited by Robert T. Golembiewski, Frank Gibson, Geoffrey Y. Cornog
Rand McNally College, 1972
Buku Teks