United States. Bureau of Labor Statistics. "Technical Notes," in United States. Bureau of Labor Statistics. "May 1981," PPI Detailed Report (May 1981) : 90-95. https://fraser.stlouisfed.org/title/63/item/21546/toc/44145 , accessed on April 18, 2024.
United States. Bureau of Labor Statistics. "Technical Notes," in United States. Bureau of Labor Statistics. "May 1981," PPI Detailed Report (May 1981) : 90-95. https://fraser.stlouisfed.org/title/63/item/21546/toc/44145 , accessed on April 18, 2024.