Sparrow, John, 1906-
Published for the British Council and the National Book League by Longmans, Green, 1992
Buku Teks SO
Mettem, Christopher J.
Spon Press, 2011
Buku Teks SO
Bridges, William
Addison-Wesley, 1991
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Pugsley, Sir Alfred
London: Edward Arnold, 1968
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Waller, Robert James
Warner Books, 1992
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