Lynch, Tony
Cambridge University Press, 1995
Buku Teks
Swan, Michael, author
Cambridge University Press, 1993
Buku Teks
Jones, Leo
Cambridge University Press, 1989
Buku Teks
King, Gareth, author
Routledge, 2005
Buku Teks
O`Neill, Robert
Longman, 1990
Buku Teks