United States. Bureau of Labor Statistics. "Nonfinancial Corporations - Appendix - Quarterly Data," in United States. Bureau of Labor Statistics. "Second Quarter 2002 [Preliminary]," Productivity and Costs (August 9, 2002) : 21-21. https://fraser.stlouisfed.org/title/131/item/55946/toc/447221 , accessed on April 24, 2024.