Source: J. Shiskin At NBER, January 29, 1965
This NBER data series m16018 appears on the NBER website in Chapter 16 at http://www.nber.org/databases/macrohistory/contents/chapter16.html.
NBER Indicator: m16018
Release: NBER Macrohistory Database
National Bureau of Economic Research, Cumulated Net Diffusion Index, Fifty-Four Roughly Coincident Series, Six Month Span for United States [M16018USM460SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M16018USM460SNBR, May 6, 2016.