United States. Bureau of Labor Statistics. "Business Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Preliminary Fourth-Quarter and Annual Averages for 2000," Productivity and Costs (February 7, 2001) : 15-15. https://fraser.stlouisfed.org/title/131/item/55774/toc/445620 , accessed on May 2, 2024.