United States. Bureau of Labor Statistics. "Union Wages, Hours, and Working Conditions of Motortruck Drivers, June 1, 1939 : Bulletin of the United States Bureau of Labor Statistics, No. 676," Union Wages and Hours : Local Truckdrivers and Helpers (1940). https://fraser.stlouisfed.org/title/3960/item/494360, accessed on August 6, 2024.