Davis, David Howard, author
Nelson-Hall Publishers, 1999
Buku Teks
Huntington, Samuel P., author
The Belknap Press, 1981
Buku Teks
McCarthy, Eugene J.
Macmillan, 1962
Buku Teks
Epstein, Edwin M., author
Prentice-Hall, 1969
Buku Teks
edited by Howard J. Wiarda, Harvey F. Kline
Westview Press, 2007
Buku Teks