Wootton, Barbara
Macmillan, 1992
Buku Teks
Blackstone Press, 1996
Buku Teks
Rawlings, Philip, author
Longman, 1999
Buku Teks
Jackson, R.M. (Richard Meredith), 1903-1986, author
Penguin Books, 1972
Buku Teks
Powell, Edward, author
Oxford University Press, 1989
Buku Teks