Hough, Michael
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Buku Teks SO
edited by Irwin Press M. Estellie Smith
Macmillan , 1980
Buku Teks SO
Sievert, Thomas
Spon Press, 2003
Buku Teks SO
Mumford, Lewis
Harcourt, Brace, 1938
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