United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "June 1990," PPI Detailed Report (June 1990) : 3-4. https://fraser.stlouisfed.org/title/63/item/21656/toc/139852 , accessed on April 19, 2024.
United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "June 1990," PPI Detailed Report (June 1990) : 3-4. https://fraser.stlouisfed.org/title/63/item/21656/toc/139852 , accessed on April 19, 2024.