United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "May 1987," PPI Detailed Report (May 1987) : 3-3. https://fraser.stlouisfed.org/title/63/item/21618/toc/132851 , accessed on May 11, 2024.
United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "May 1987," PPI Detailed Report (May 1987) : 3-3. https://fraser.stlouisfed.org/title/63/item/21618/toc/132851 , accessed on May 11, 2024.