Trask, R.L.
London, 1998
Buku Referensi
Siobhan Chapman
Oxford University Press, 2005
Buku Teks
Edinburgh, Edinburgh University Press, 2005
Buku Referensi
Vernon, Mark
RajaGrafindo Persada, 2011
Buku Teks
Hayward, Susan
Routledge , 2006
Buku Referensi