Penguin Books, 1987
Buku Referensi
Burton, William.
Simon & Schuster Macmillan, 1992
Buku Teks
Robert, Collin
Paris : Harper Collins Publisher, 2000
Buku Referensi
Ray, Mary Barnard, author
Thomson West, 2006
Buku Teks
Ray, Mary Barnard, author
Thomson West, 2008
Buku Teks