Billups, Robert S. (Robert Strother). Entrance Rates and Full-Time Hours of Common Laborers Employed by Cities: September, 1935 : Bulletin of the United States Bureau of Labor Statistics, No. 627 , Washington, D.C: U.S. G.P.O., 1937, https://fraser.stlouisfed.org/title/4144, accessed on February 12, 2026.