Soja, Edward W.
Blackwell Pub , 2000
Buku Teks
Jarvis, Helen
Prentice-Hall, 2001
Buku Teks
edited by Andrew Blowers, Chris Hammett and Philip Sarre
Hutchinson Educational in association with the Open University Press, 1974
Buku Teks
Gutkind, E. A.
The Free Press of Glencoe, 1963
Buku Teks
Mercer, Charles
Penguin Books, 1975
Buku Teks