Use Google Scholar and focus on last 2-3 year (2021 to 2023) and look for resear

Use Google Scholar and focus on last 2-3 year (2021 to 2023) and look for research on the variables we consider in our analysis, i.e. countries where billionaires reside, industries in which they made their fortunes, self made vs not, and any research related to billionaires’ genders