Singh, Robert
Polity Press, 2002
Buku Teks
Frank, Jerome
Princeton University press, 1973
Buku Teks
Jenkins, Jeffrey A.
Jones and Bartlett Publishers LLC , 2011
Buku Teks
Jacob, Herbert, 1933-
Yale University Press, 1996
Buku Teks
Huntington, Samuel P.
The Belknap Press, 1981
Buku Teks