Kegley, Charles William, Jr., author
St. Martin`s Press, 1997
Buku Teks
by Steven L. Spiegel [and others]
Thomson Wadsworth, 2005
Buku Teks
Frieden, Jeffry A., author
W.W. Norton, 2016
Buku Teks
Kaplan, Morton A., author
John Wiley & Sons, 1961
Buku Teks
Reynolds, Charles, author
Martin Robertson, 1973
Buku Teks