Chapman, Richard A.
Constable, 1970
Buku Teks
Stout, Hiram Miller
The University of North Carolina Press, 1938
Buku Teks
Monck, Bosworth
Phoenix House Limited, 1952
Buku Teks
R. A. W. Rhodes [and others]
Open University press, 2003
Buku Teks
O`toole, Barry J.
Routledge, 2006
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