United States. Bureau of Labor Statistics. Technology and Labor in Five Industries: Bakery Products, Concrete, Air Transportation, Telephone Communication, Insurance : Bulletin of the United States Bureau of Labor Statistics, No. 2033 , Washington, D.C: U.S. Dept. of Labor, Bureau of Labor Statistics, September 1979, https://fraser.stlouisfed.org/title/4858, accessed on October 6, 2024.