Braun, Hans-Joachim
The German economy in the twentieth century
Routledge, 1990
 Buku Teks SO
Brecht, Arnold
Political theory: the foundations of twentieth-century political thought
Princenton University Press, 1968
 Buku Teks SO
The Routledge dictionary of twentieth-century political thinkers
edited by Robert Benewick and Philip Green
Routledge , 1992
 Buku Teks SO
Australian conservatism : essays in twentieth century political history
editor, Cameron Hazlehurst
Australian National University Press, 1979
 Buku Teks SO
Schapiro, J. Salwyn
The world in crisis : political and social movement in the twentieth century
McGraw-Hill, 1950
 Buku Teks