United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "December 1984," PPI Detailed Report (December 1984) : 16-16. https://fraser.stlouisfed.org/title/63/item/21589/toc/57163 , accessed on April 19, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "December 1984," PPI Detailed Report (December 1984) : 16-16. https://fraser.stlouisfed.org/title/63/item/21589/toc/57163 , accessed on April 19, 2024.