[1] https://www.statista.com/statistics/1093666/china-per-capita-gross-domestic-product-gdp-by-province/
[2] https://www.statista.com/statistics/1093666/china-per-capita-gross-domestic-product-gdp-by-province/
[3] https://www.hsph.harvard.edu/nutritionsource/selenium/#:~:text=Selenium%20is%20an%20essential%20component,the%20metabolism%20of%20thyroid%20hormones.