Series Is Presented Here As Three Variables-- (1)--Original Data, 1850-1894 (2)--Original Data, 1890-1914 (3)-- Original Data, 1913-1968. Source: G.F. Warren And F.A. Pearson, "Prices" Pp. 12-13
This NBER data series m04048a appears on the NBER website in Chapter 4 at http://www.nber.org/databases/macrohistory/contents/chapter04.html.
NBER Indicator: m04048a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Index of Wholesale Prices, Variable Group Weights for United States [M0448AUSM323NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M0448AUSM323NNBR/, October 4, 2015.