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
McIlroy, John, author
Manchester University Press , 1995
Buku Teks
Richards, Denis, author
Longman, Green, 1952
Buku Teks