Source: NBER Deflated Federal Reserve Board Data By Dividing Series 06002 (Index Of Department Store Sales) By Series 06002A (Department Store Sales, Adjusted For Trend And Price Change).
This NBER data series m06002ba appears on the NBER website in Chapter 6 at http://www.nber.org/databases/macrohistory/contents/chapter06.html.
NBER Indicator: m06002ba
Release: NBER Macrohistory Database
National Bureau of Economic Research, The Physical Volume of Department Store Sales for United States [M062BAUSM343SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M062BAUSM343SNBR/, October 4, 2015.