Crystal, David, 1941-
Cambridge University Press, 1995
Buku Referensi
editor in chief Paul Procter
Cambridge University Press, 1995
Buku Referensi
Lutz, William D.
Cambridge University Press, 1994
Buku Referensi
edited by Ian Qusby
Cambridge University Press, 1988
Buku Referensi
Peters, Pam
Cambridge University Press, 2006
Buku Referensi