Ben Jackson, Robert Saunders, editors
Cambridge University Press, 2012
Buku Teks
Watkins, Alan
Duckworth, 1991
Buku Teks
Keegan, William
Allen Lane, 1984
Buku Teks
edited by Richard A. Chapman and A. Dunsire
George Allen and Unwin, 1971
Buku Teks
Jones, Bill
Manchester University Press, 1991
Buku Teks