Yeager, Rodger, author
Westview Press, 1989
Buku Teks
Wilding, Michael, author
Penguin Books , 1984.
Buku Teks
Keegan, William, author
Allen Lane, 1984
Buku Teks
Garnett, David, author
Longman , 1991
Buku Teks
King, Peter, author
Routledge, 2016
Buku Teks