Source: Bureau Of Labor Statistics, Bulletin No. 1312-8, "Employment And Earnings In The United States, 1909-1971", Pp. 36 And 608.
This NBER data series m08322 appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: m08322
Release: NBER Macrohistory Database
National Bureau of Economic Research, Labor Turnover, New Hires, Manufacturing for United States [M08322USM497NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M08322USM497NNBR/, August 4, 2015.