United States. Bureau of Labor Statistics. "Footnotes," in United States. Bureau of Labor Statistics. "Private Business, Nonfarm Business, and Manufacturing Sectors : First Quarter 1978 (and Data for Nonfinancial Corporations, Fourth Quarter 1977)," Productivity and Costs (April 25, 1978) : 13-13. https://fraser.stlouisfed.org/title/131/item/55977/toc/494969 , accessed on April 19, 2024.