Cambridge University Press, 2004
Buku Teks
Arnold, Karl-Heinz
Panorama GDR, 1976
Buku Teks
Bauer, Raymond A., author
MIT Press, 1966
Buku Teks
edited and introduced by Andrew Shonfield and Stella Shaw
Heinemann Educational Books, 1972
Buku Teks
Hall, Jerome
Lousiana State University Press, 1963
Buku Teks