Sharp, Andrew
Clarendon Press, 1963
Buku Teks
Wright, J. F. H.
Hale & Iremonger, 1980
Buku Teks
Parkin, Andrew
Macmillan, 1982
Buku Teks
Sydney Hicks,Smith & Sons Pty LTD 1973,
Buku Referensi
Ward, Russel, author
Heinemann educational Australia, 1977
Buku Teks