Gilpin, Robert, author
Princeton University Press, 1987
Buku Teks
Schiavo-Campo, Salvatore
Winthrop Publishers, Inc., 1978
Buku Teks
Oatley, Thomas, author
Pearson, 2012
Buku Teks
Balaam, David N., 1950-, author
Pearson Education, 2014
Buku Teks
Balaam, David N., 1950-, author
Pearson/Prentice Hall, 2005
Buku Teks