United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "January 1984," PPI Detailed Report (January 1984) : 15-15. https://fraser.stlouisfed.org/title/63/item/21578/toc/218460 , accessed on March 19, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "January 1984," PPI Detailed Report (January 1984) : 15-15. https://fraser.stlouisfed.org/title/63/item/21578/toc/218460 , accessed on March 19, 2024.