Supperstone, Michael, author
Longman, 1994
Buku Teks
Goldstein, Paul, author
Little, Brown, 1989
Buku Teks
Ding, Julian
Swett and Maxwell Asia, 1999
Buku Teks
Addison, Neil, author
Blackstone Press Limited, 1998
Buku Teks
Hegland, Kenney, author
St. Paul, Minn, 2003
Buku Teks