United States. Bureau of Labor Statistics. "Durable Manufacturing Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Third Quarter 2001 [Revised]," Productivity and Costs (December 6, 2001) : 16-16. https://fraser.stlouisfed.org/title/131/item/55944/toc/446208 , accessed on May 1, 2024.