United States. Bureau of Labor Statistics. "Railroads," in United States. Bureau of Labor Statistics. "April 1986," PPI Detailed Report (April 1986) : 133-134. https://fraser.stlouisfed.org/title/63/item/21605/toc/60415 , accessed on April 17, 2024.
United States. Bureau of Labor Statistics. "Railroads," in United States. Bureau of Labor Statistics. "April 1986," PPI Detailed Report (April 1986) : 133-134. https://fraser.stlouisfed.org/title/63/item/21605/toc/60415 , accessed on April 17, 2024.