Minife, James M., author
McClelland and Stewart Limited, 1964
Buku Teks
Institute of International Relations , 1988
Buku Teks
F.W. Chesire, 1968
Buku Teks
Gardner, Richard N.
Dell Publishing Co., Inc., 1965
Buku Teks
Gardner, Paul F.
Westview Press, 1997
Buku Teks