Scobie, Janet I.
George Allen and Unwin, 1959
Buku Teks
Doff, Adrian
Cambridge University Press, 2011
Multimedia
Doff, Adrian
Cambridge University Press, 2011
Multimedia
Tomasowa, Francien Herlen
Universitas Brawijaya, 2005
Buku Teks
Sambrook, G.A.
Longman, 1947
Buku Teks