Berkowitz, Gerald M.
Longman, 1994
Buku Teks
edited by Alexander Baltzly, A. William Salomone
Appleton-Century-Crofts, 1950
Buku Teks
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
Buku Teks
Varga, Eugen, 1879-1964
Foreign Languages Publishing House, 1961
Buku Teks
Kohn, Hans
D. Van Nostrand, 1965
Buku Teks