United States. Bureau of Labor Statistics. "Nonfarm Business Sector," in United States. Bureau of Labor Statistics. "Nonfinancial Corporate Sector : Annual Data for 1980," Productivity and Costs (February 26, 1981) : 7-7. https://fraser.stlouisfed.org/title/131/item/55900/toc/437777 , accessed on May 4, 2024.