https://www.census.gov/content/dam/Census/library/publications/2019/demo/p60-266.pdf
https://beyond-coal.eu/wp-content/uploads/2019/12/Sandbag-CoalBook2019-WEB.pdf
https://www.globalwitness.org/documents/20617/EACOP_report_-_FINAL_PDF.pdf
https://www.nature.com/articles/s41598-021-00053-8.pdf