United States. Bureau of Labor Statistics. "Footnotes," in United States. Bureau of Labor Statistics. "Fourth-Quarter and Annual Averages 1987, Business, Nonfarm Business, and Manufacturing and 1987 Annual Averages for Nonfinancial Corporations," Productivity and Costs (March 3, 1988) : 13-13. https://fraser.stlouisfed.org/title/131/item/55957/toc/454327 , accessed on April 24, 2024.