Department of State, 1949
Buku Teks
McCormack, T.H.
University Tutonial Press, 1980
Buku Teks
Norton, Thomas James
America`s Future, 1946
Buku Teks
Mowbray, Albert H.
McGraw-Hill, c1969
Buku Teks
edited by Allan Nevins and Louis M. Hacker
D.C. Heath, 1943
Buku Teks