1. World Bank. (2021). GDP per capita (current US$). Retrieved April 26, 2022, from https://data.worldbank.org/indicator/NY.GDP.PCAP.CD.
2. Saez, E. (2020). Striking it richer: The Evolution of Top Incomes in the United States (Updated with 2018 estimates). Retrieved April 26, 2022, from https://elsa.berkeley.edu/~saez/saez-UStopincomes-2018.pdf
3. Wilkinson, R., & Pickett, K. (2010). The spirit level: Why equality is better for everyone. Penguin.
4. Wilkinson, R., & Pickett, K. (2018/2020). The inner level: How more equal societies reduce stress, restore sanity and improve everyone's well-being. Penguin Books.
5. Payne, B. K., Brown-Iannuzzi, J. L., & Hannay, J. W. (2017). Economic inequality increases risk taking. Proceedings of the National Academy of Science USA, 114(18), 4643–4648.