United States. Bureau of Labor Statistics. "Manufacturing Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Second Quarter 2001 [Preliminary]," Productivity and Costs (August 7, 2001) : 14-14. https://fraser.stlouisfed.org/title/131/item/55964/toc/445979 , accessed on April 18, 2024.