United States. Bureau of Labor Statistics. "Nonfarm Business Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Second Quarter 2003 [Preliminary]," Productivity and Costs (August 7, 2003) : 19-19. https://fraser.stlouisfed.org/title/131/item/55776/toc/446909 , accessed on April 18, 2024.