1. United Nations, Department of Economic and Social Affairs, Population Division (2017) World Population Prospects: The 2017 Revision, custom data acquired via website.
https://esa.un.org/unpd/wpp/DataQuery/
. Accessed 24 April 2018
2. World Economic Forum: These are the world’s most crowded cities webpage.
https://www.weforum.org/agenda/2017/05/these-are-the-world-s-most-crowded-cities/
. Accessed 5 Aug 2018
3. World Economic Forum: Which are the world’s most crowded cities?
https://www.weforum.org/agenda/2015/11/which-are-the-worlds-most-crowded-cities
. Accessed 5 Aug 2018
4. United Nations, Department of Economic and Social Affairs, Population Division The World’s Cities in 2016 – Data Booklet (ST/ESA/ SER.A/392) (2016)
5. United Nations Educational, Scientific and Cultural Organization (UNESCO), Natural Sciences, Science and Technology, Sustainable Engineering.
http://www.unesco.org/new/en/natural-sciences/science-technology/engineering/sustainable-engineering/
. Accessed 24 April 2018