Hill, L.A.
Oxford University Press, 1977
Buku Teks SO
Foers, E.
Oxford University Press, 1957
Buku Teks SO
edited by Gareth Williams, Martin Kenyon and Lynn Williams
Overseas Student Trust, 1987
Buku Referensi
The British Council, 1980
Buku Teks
edited by David McNamara, Robert Harris
Routledge, 1997
Buku Teks