United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "April 1989," PPI Detailed Report (April 1989) : 3-4. https://fraser.stlouisfed.org/title/63/item/21645/toc/234397 , accessed on April 23, 2024.
United States. Bureau of Labor Statistics. "Contents," in United States. Bureau of Labor Statistics. "April 1989," PPI Detailed Report (April 1989) : 3-4. https://fraser.stlouisfed.org/title/63/item/21645/toc/234397 , accessed on April 23, 2024.