Plumb, J.H.
The British Council by Longmans, Green, 1971
Buku Teks
Birkett, Lord, author
Penguin Books, 1961
Buku Teks
Chapman, Richard A., author
Constable, 1970
Buku Teks
Gilliat-Ray, Sophie, author
Cambridge University Press, 2010
Buku Teks
Buchanan, Robert Angus, author
Penguin, 1972
Buku Teks