Swan, Michael, author
Oxford University Press, 1995
Buku Teks
Ross, Claudia, author
Routledge, 2006
Buku Referensi
Ur, Penny, author
Cambridge University Press, 1988
Buku Teks
Nesfield, J.C.
MacMillan Press , 1978
Buku Teks
Ogden, C. K. (Charles Kay), 1889-1957, author
Kegan, 1944
Buku Teks