United States. Bureau of Labor Statistics. "Footnotes," in United States. Bureau of Labor Statistics. "Private Business, Nonfarm Business, and Manufacturing Sectors : First Quarter 1983," Productivity and Costs (April 27, 1983) : 10-10. https://fraser.stlouisfed.org/title/131/item/55770/toc/450579 , accessed on April 18, 2024.