Griffith, Ernest S.
New York University press, 1956
Buku Teks
Griffith, Ernest S.
New York University press, 1952
Buku Teks
Editor by Lawrence C.Dood; Bruce I. Oppenheimer
Congressional Quarterly Press, 1981
Buku Teks
Howard D.Samuel
Henry Holt and Company, 1953
Buku Teks
Keefe, William J., author
Prentice-Hall, 1994
Buku Teks