editor-publisher, Hack-cho Mah
Asia PR Center, 1975
Buku Teks
Tomlinson, Jim
Methuen, 1981
Buku Teks
Wells, S.J.
Cambridge University Press , 1964
Buku Teks
edited by Tony Buxton, Paul Chapman and Paul Temple
Routledge , 1994
Buku Teks
Endres, Elisabeth
Frankfurt Fischer Taschenbuch verlag GmbH 1975
Buku Teks