United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "April 1999," PPI Detailed Report (April 1999) : 3-4. https://fraser.stlouisfed.org/title/63/item/21763/toc/231546 , accessed on May 2, 2024.
United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "April 1999," PPI Detailed Report (April 1999) : 3-4. https://fraser.stlouisfed.org/title/63/item/21763/toc/231546 , accessed on May 2, 2024.