Epstein, Edwin M., author
Prentice-Hall, 1969
Buku Teks
edited by Howard J. Wiarda, Harvey F. Kline
Westview Press, 2007
Buku Teks
Sharkansky, Ira, author
McGraw-Hill, 1975
Buku Teks
Huntington, Samuel P., author
The Belknap Press, 1981
Buku Teks
edited by Stephen K. Bailey
United States Information Agency, 1973
Buku Teks