United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "December 1983," PPI Detailed Report (December 1983) : 13-13. https://fraser.stlouisfed.org/title/63/item/21577/toc/160308 , accessed on March 29, 2024.
United States. Bureau of Labor Statistics. "Coal," in United States. Bureau of Labor Statistics. "December 1983," PPI Detailed Report (December 1983) : 13-13. https://fraser.stlouisfed.org/title/63/item/21577/toc/160308 , accessed on March 29, 2024.