United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "July 1984," PPI Detailed Report (July 1984) : 14-14. https://fraser.stlouisfed.org/title/63/item/21584/toc/373215 , accessed on May 7, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "July 1984," PPI Detailed Report (July 1984) : 14-14. https://fraser.stlouisfed.org/title/63/item/21584/toc/373215 , accessed on May 7, 2024.