United States. Bureau of Labor Statistics. "Business Sector," in United States. Bureau of Labor Statistics. "Private Business, Nonfarm Business, and Manufacturing Sectors : Fourth Quarter 1981 and Annual Averages for 1981," Productivity and Costs (January 28, 1982) : 4-4. https://fraser.stlouisfed.org/title/131/item/55746/toc/438274 , accessed on April 25, 2024.