Crystal, David, 1941-, author
Cambridge University Press, 1991
Buku Referensi
Peters, Pam, author
Cambridge University Press, 2006
Buku Referensi
Cambridge University Press, 2005
Buku Referensi
New York Cambridge University Press 1991
Buku Referensi
Ceramella, Nick, author
Cambridge University Press, 2008
Multimedia