1. The World’s Cities in 2018: Data Booklet,2018
2. 9 out of 10 People Worldwide Breathe Polluted Air, but More Countries Are Taking Actionhttps://www.who.int/news-room/detail/02-05-2018-9-out-of-10-people-worldwide-breathe-polluted-air-but-more-countries-are-taking-action
3. Ambient Air Pollution: A Global Assessment of Exposure and Burden of Disease,2016
4. State of Global Air 2019http://stateofglobalair.org/
5. Data—World Bank Open Datahttps://data.worldbank.org/indicator/NY.GDP.PCAP.CD