United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "October 1984," PPI Detailed Report (October 1984) : 13-13. https://fraser.stlouisfed.org/title/63/item/21587/toc/157404 , accessed on April 24, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "October 1984," PPI Detailed Report (October 1984) : 13-13. https://fraser.stlouisfed.org/title/63/item/21587/toc/157404 , accessed on April 24, 2024.