United States. Bureau of Labor Statistics. "Nondurable Manufacturing Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Second Quarter 1988 [Preliminary]," Productivity and Costs (August 4, 1988) : 17-17. https://fraser.stlouisfed.org/title/131/item/55807/toc/454937 , accessed on April 24, 2024.