Routledge, 2004
Buku Teks
edited by Michael Byram
Routledge, 2000 ; 2004
Buku Referensi
Donald Freeman and Jack C. Richardsand , author
Cambridge Cambridge University Press 1996
Buku Teks
Brown, Douglas, author
Pearson Longman, 2007
Buku Teks
Cook, Vivian, author
ARNOLD, 2001
Buku Teks