United States. Bureau of Labor Statistics. "Manufacturing Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Third Quarter 1990 [Preliminary]," Productivity and Costs (November 6, 1990) : 15-15. https://fraser.stlouisfed.org/title/131/item/55915/toc/461188 , accessed on April 25, 2024.