1. Pew Research Centre. (2015, April 2). Chapter 1: Main Factors Driving Population Growth. Retrieved from Pew Research Centre: https://www.pewforum.org/2015/04/02/main-factors-driving-population-growth/
2. United Nations Population Division. (2019, August 23). Total fertility by region,subregion and country. Retrieved from World Population Prospects: https://population.un.org/wpp/Download/Standard/Fertility/
3. United Nations Department of Social and Economics Affairs. (2017, June 31). World population projected to reach 9.8 billion in 2050, and 11.2 billion in 2100. Retrieved from United Nations: https://www.un.org/development/desa/en/news/population/world-population-prospects-2017.html
4. Population and development report