Cruse, Alan, author
German : Edinburgh University Press, 2006
Buku Referensi
New York Cambridge University Press 1974
Buku Teks
Hofmann, Th. R.
London Longman 1995,
Buku Teks
Griffths, Patrick, author
Edinburgh University Press, 2006
Buku Teks
New York : Routledge , 2005
Buku Teks