United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "December 1982," PPI Detailed Report (December 1982) : 14-14. https://fraser.stlouisfed.org/title/63/item/21565/toc/227957 , accessed on April 25, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "December 1982," PPI Detailed Report (December 1982) : 14-14. https://fraser.stlouisfed.org/title/63/item/21565/toc/227957 , accessed on April 25, 2024.