Source: Ruth P. Mack, Machine Tape Of May 16, 1958.
This NBER data series m04203 appears on the NBER website in Chapter 4 at http://www.nber.org/databases/macrohistory/contents/chapter04.html.
NBER Indicator: m04203
Release: NBER Macrohistory Database
National Bureau of Economic Research, Index of Wholesale Prices of Semi-Processed Goods Other Than Foods for United States [M04203USM349NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M04203USM349NNBR/, October 13, 2015.