Series Is Presented Here As Three Variables--(1)--Seasonally Adjusted Data, 1921-1941 (2)--Original Data, 1939-1946 (3)--Seasonally Adjusted Data, 1946-1969. Source: Barger And Klein From Data Developped By Barger In "Outlay And Income In The United States, 1921-1938 (New York NBER, 1942)
This NBER data series q08260a appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: q08260a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Gross National Product for United States [Q0860AUSQ027SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q0860AUSQ027SNBR/, August 1, 2015.