David L. Sam; John W. Berry, editor
Cambridge University Press, 2006
Buku Teks
Mee, Jon, author
Cambridge University Press , 2010
Buku Teks
Crystal, David, 1941-, author
Cambridge University Press, 1997
Buku Referensi
Gutteridge, Anne C.
Cambridge University Press, 1983
Buku Referensi
edited by James Crawford and Martti Koskenniemi
Cambridge University Press, 2012
Buku Teks