United States. Bureau of Labor Statistics. "Footnotes," in United States. Bureau of Labor Statistics. "Private Business, Nonfarm Business, and Manufacturing Sectors : First Quarter 1980 (and Data for Nonfinancial Corporations, Fourth Quarter 1979)," Productivity and Costs (April 25, 1980) : 11-11. https://fraser.stlouisfed.org/title/131/item/55894/toc/437480 , accessed on May 2, 2024.