Gorbachev, Mikhail
Moral lessons of twentieth century : Gorbachev and Ikeda on Buddhism and communism / Mikhail Gorbachev and Daisaku Ikeda
I.B. Tauris, 2005
 Buku Teks
MacIntyre, Alasdair
A short history of ethics: a history of moral philosophy from the Homeric Age to the Twentieth Century
Rontledge , 1998
 Buku Teks
Revolutions of the late twentieth century
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
 Buku Teks
Varga, Eugen, 1879-1964
Twentieth century capitalism
Foreign Languages Publishing House, 1961
 Buku Teks
Kohn, Hans
African nationalism in the twentieth century
D. Van Nostrand, 1965
 Buku Teks