United States. Bureau of Labor Statistics. "Durable Manufacturing Sector," in United States. Bureau of Labor Statistics. "Preliminary Fourth-Quarter Measures and Annual Averages, 1997," Productivity and Costs (February 10, 1998) : 11-11. https://fraser.stlouisfed.org/title/131/item/55932/toc/435058 , accessed on May 2, 2024.