Norton, Thomas James
America`s Future, Inc., 1946
Buku Teks
Mitchell, Broadus
Oxford University Press, 1964
Buku Teks
edited by Richard L. Perry and John C. Cooper
American Bar Foundation, 1964
Buku Teks
Mussatti, James
D. Van Nostrand Company, Inc., 1960
Buku Teks
United States Information Agency, 1987
Buku Teks