United States. Bureau of Labor Statistics. "Productivity and Costs by Industry, 2003 : Productivity and Costs by Industry, 2003, USDL 05-1599," Productivity and Costs by Industry (August 26, 2005). https://fraser.stlouisfed.org/title/9618/item/703979/content/pdf/prin_20050826, accessed on June 17, 2026.