United States. Bureau of Labor Statistics. "Footnotes," in United States. Bureau of Labor Statistics. "Private Business, Nonfarm Business, and Manufacturing Sectors : Second Quarter 1978," Productivity and Costs (July 27, 1978) : 16-16. https://fraser.stlouisfed.org/title/131/item/55879/toc/494998 , accessed on May 1, 2024.