Findley, Carter V., author
Wadsworth and Cengage Learning, 2011
Buku Teks
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
Buku Teks
Keylor, William R., 1944-
Oxford University Press, 1996
Buku Teks
Ewen, David, author
Prentice Hall, 1968
Buku Referensi
Black, C.E., author
Alfred A. Knopf, 1961
Buku Teks