Armstrong, Michael
[Publisher not identified], [Date of publication not identified]
Buku Teks SO
Vause, R.
Macmillan, 1975
Buku Teks
United Nations Centre for Human Settlements (Habitat), 1991
Buku Referensi
Smyth, Terry
Macmillan, 1996
Buku Teks
Armstrong, Michael
Crest Publishing House, 1999
Buku Teks SO