United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "May 1989," PPI Detailed Report (May 1989) : 3-4. https://fraser.stlouisfed.org/title/63/item/21644/toc/256316 , accessed on April 24, 2024.
United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "May 1989," PPI Detailed Report (May 1989) : 3-4. https://fraser.stlouisfed.org/title/63/item/21644/toc/256316 , accessed on April 24, 2024.