United States. Bureau of Labor Statistics. "Business Sector - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Second Quarter 1992 [Preliminary]," Productivity and Costs (August 11, 1992) : 14-14. https://fraser.stlouisfed.org/title/131/item/55821/toc/464936 , accessed on April 25, 2024.