Willrich, Mason
The Free Press, 1975
Buku Teks
Organski, A.F.K., author
Alfred A. Knopf, 1969
Buku Teks
Russett, Bruce, author
Wadsworth, 2010
Buku Teks
Kegley, Charles W. (Charles William), Jr., author
Wadsworth, 2009
Buku Teks
Rourke, John T., author
McGraw-Hill, 2010
Buku Teks