United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "October 1982," PPI Detailed Report (October 1982) : 15-15. https://fraser.stlouisfed.org/title/63/item/21563/toc/164785 , accessed on May 9, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "October 1982," PPI Detailed Report (October 1982) : 15-15. https://fraser.stlouisfed.org/title/63/item/21563/toc/164785 , accessed on May 9, 2024.