Wallace, Michael J., author
Cambridge University Press, 2004
Buku Teks
Baker, Michael J., author
Macmillan, 1991
Buku Teks
Allwright, Dick, author
Cambridge University Press, 1991
Buku Teks
Brown, James Dean, author
Cambridge University Press, 1988
Buku Teks
McDonough, Jo
Arnold, 1997
Buku Teks