Producer Price Indexes for Bituminous Coal by Region
United States. Bureau of Labor Statistics. "Producer Price Indexes for Bituminous Coal by Region," in United States. Bureau of Labor Statistics. "March 1978," PPI Detailed Report (March 1978) : 61-61. https://fraser.stlouisfed.org/title/63/item/21508/toc/250317 , accessed on April 25, 2024.