Oatley, Thomas, author
Pearson, 2012
Buku Teks
Gilpin, Robert, author
Princeton University Press, 1987
Buku Teks
edited by John Ravenhil
Oxford University Press, 2014
Buku Teks
Balaam, David N., 1950-, author
Pearson/Prentice Hall, 2005
Buku Teks
Balaam, David N., 1950-, author
Prentice-Hall, 1996
Buku Teks