Smith, David, editor
Macmillan, 1995
Buku Teks
editor, Brian J. Rusbridge
Municipal Journal Limited, 1990
Buku Referensi
Andy Mantell, Terry Scragg, editor
Learning matters Ltd., 2008
Buku Teks
Ernest
Kogan Page , 1995
Buku Teks
Christopher, Elphis, author
Temple Smith, 1980
Buku Teks