edited by Andrew Blowers, Chris Hammett and Philip Sarre
Hutchinson Educational in association with the Open University Press, 1974
Buku Teks SO
Gutkind, E.A.
Free Press of Glencoe, 1963
Buku Teks SO
Orum, Anthony M.
Blackwell, 2003
Buku Teks SO
Mumford, Lewis
Harcourt, Brace, 1938
Buku Teks SO
Mercer, Charles
Penguin Books, 1975
Buku Teks SO