United States. Bureau of Labor Statistics. "Manufacturing Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Second Quarter 1988 [Preliminary]," Productivity and Costs (August 4, 1988) : 15-15. https://fraser.stlouisfed.org/title/131/item/55807/toc/454938 , accessed on June 28, 2024.