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