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.
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Buku Teks SO
Orum, Anthony M.
Blackwell, 2003
Buku Teks SO
Bergel, Egon Ernest
McGraw-Hill, 1955
Buku Teks SO
Gleeson, Brendan, 1964- author
Routledge, 2014
Buku Teks SO