Aston, Elaine, author
Routledge, 1999
Buku Referensi
Bornatsky, I., author
Foreign Languages, 1963
Buku Teks
Demkin, Joseph A., editor
John Wiley & Sons, 2001
Buku Referensi
Armstrong, Michael, author
Kogan Page Limited, 1995
Buku Referensi
edited by Ray Prytherch
Gower , 1990
Buku Teks