Bastin, John
Prentice Hall of Australia, 1977
Buku Teks
King, John Kerry
Macmillan, 1959
Buku Teks
ASEAN Focus Group ; edited by Peter Church
Allen & Unwin, 1995
Buku Teks
Williams, Lea E.
Oxford University Press, Inc, 1976
Buku Teks
Progressio, 1972
Buku Teks