Source: J. Shiskin At NBER, January 29, 1965
This NBER data series m16014 appears on the NBER website in Chapter 16 at http://www.nber.org/databases/macrohistory/contents/chapter16.html.
NBER Indicator: m16014
Release: NBER Macrohistory Database
National Bureau of Economic Research, Comprehensive Diffusion Index, Fifty-Four Roughly Coincident Series, Six Month Span for United States [M16014USM509SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M16014USM509SNBR, February 5, 2016.