Black, C.E.
Twentieth Century Europe: a history
Alfred A. Knopf, 1966
 Buku Teks SO
Nichols, Jeannette P.
Twentieth century United States : a history
D. Appleton-Century, 1943
 Buku Teks SO
Readings in twentieth-century European history
edited by Alexander Baltzly, A. William Salomone
Appleton-Century-Crofts, 1950
 Buku Teks SO
Readings in Twentieth-Century European History
edited by Alexander Baltzly
Appleton-Century-Crofts, Inc, 1950
 Buku Teks SO
Reese, Trevor R.
Australia in the twentieth century : a political history
F.W. Cheshire, 1964
 Buku Teks SO