Marshall, Brenda K., author
Routledge, 1992
Buku Teks
Helen L. Van Hoozer [and others]
Appleton Century Crofts, 1987
Buku Teks
Ur, Penny, author
Cambridge University Press, 2006
Buku Teks
Ur, Penny, author
Cambridge University Press, 1999
Buku Teks
inda Gask, Bulent Coskun, David Baron
Wiley- Blackwell, 2011
Buku Teks