Ron White...[et al.]
Cambridge University Press , 1991
Buku Teks
Tomasowa, Francien Herlen
Universitas Brawijaya , 2005
Buku Teks
Eastwood, John
Oxford University Press, 1994
Buku Teks
Scobie, Janet I.
George Allen and Unwin, 1959
Buku Teks
Puchta, Herbert
Cambridge University Press, 2010
Multimedia