United States. Bureau of Labor Statistics. "Nonfarm Business Sector - Appendix - Annual Data," in United States. Bureau of Labor Statistics. "Third Quarter 1999 [Preliminary]," Productivity and Costs (November 12, 1999) : 13-13. https://fraser.stlouisfed.org/title/131/item/55937/toc/441602 , accessed on March 28, 2024.