Ambrose, Peter
Penguin Books,, 1975
Buku Teks
Tomlinson, Jim, author
Methuen, 1981
Buku Teks
Ben Jackson, Robert Saunders, editors
Cambridge University Press, 2012
Buku Teks
Berry, Craig, author
Palgrave Macmillan, 2016
Buku Teks
edited by Peter Taylor-Gooby
Oxford University Press, 2013
Buku Teks