Button, John, author
Cassell, 1995
Buku Referensi
Schapiro, J. Salwyn
McGraw-Hill Book Company, Inc., 1950
Buku Teks
Achmad Jainuri, author
McGill University Montreal, 1992
Buku Teks
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
Buku Teks
Varga, Eugen, 1879-1964, author
Foreign Languages Publishing House, 1961
Buku Teks