Richardson, Boyce
New Press, 1972
Buku Teks
Barlow, Mike, author
John Wiley & Sons, 2019
Buku Teks
edited by Andrew Blowers, Chris Hammett and Philip Sarre
Hutchinson Educational in association with the Open University Press, 1974
Buku Teks
Geddes, Patrick
Williams & Norgate, 1949
Buku Teks
Barnett, Jonathan, author
Planners Press, 2003
Buku Teks