United States. Bureau of Labor Statistics. "Footnotes," in United States. Bureau of Labor Statistics. "Third Quarter 1991 [Revised] : Business, Nonfarm Business, Manufacturing, and Nonfinancial Corporations," Productivity and Costs (January 3, 1992) : 15-15. https://fraser.stlouisfed.org/title/131/item/55817/toc/463896 , accessed on May 1, 2024.