Droz, Jacques, author
Harper & Row, 1967
Buku Teks
Buku Teks
Robertson, Priscilla, author
University Press, 1971
Buku Teks
Link, Robert G., author
Columbia University Press, 1959
Buku Teks
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
Buku Teks