Woodham, Jonatham M.
Twentieth-Century design
Oxford University Press, 1997
 Buku Teks SO
Chant, Christopher
Twentieth century war machines
London: Chancellor Press, 1999,
 Buku Referensi
Revolutions of the late twentieth century
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
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Black, C.E.
Twentieth Century Europa: a history
Alfred A. Knopf, 1961
 Buku Teks SO
Varga, Eugen, 1879-1964
Twentieth century capitalism
Foreign Languages Publishing House, 1961
 Buku Teks SO