Stevenson, Deborah
Open University Press, 2003
Buku Teks SO
edited by Peter Scott
Georgian House, 1978
Buku Teks SO
Tonkiss, Fran
Polity Press, 2013
Buku Teks SO
Schwab, William A.
Prentice-Hall, 1992
Buku Teks SO
edited by Andrew Blowers, Chris Hammett and Philip Sarre
Hutchinson Educational in association with the Open University Press, 1974
Buku Teks SO