Cambridge University Press, 2004
Buku Teks
Nation, I.S.P., author
Cambridge University Press, 2013
Buku Teks
Ur, Penny, author
Cambridge University Press, 1999
Buku Referensi
Ayer, A. J. (Alfred Jules), 1910-1989, author
Penguin Books, 1980
Buku Teks
edited by Susan Brindley
Routledge, 1993
Buku Teks