1. Department of Statistics Singapore. (2018). Singapore in figures 2018. Retrieved from http://www.singstat.gov.sg/-/media/files/publications/reference/sif2018.pdf
2. UN-Habitat Urban Data. (2018). The world’s cities in 2018: The United Nations. Retrieved from http://data.un.org/en/events/citiesday/assets/pdf/the_worlds_cities_in_2018_data_booklet.pdf
3. World Bank. (2017). GDP per capita 2017 (Current USD). Retrieved from https://data.worldbank.org/indicator/NY.GDP.PCAP.CD
4. Word Resources Institute. (2015). Singapore in figures 2018. Retrieved from https://www.wri.org › blog › 2015/08 › ranking-world-s-most-water-stressed-countries-in-2040