Series Is Presented Here As Two Variables--(1)--Seasonally Adjusted Data, 1921-1939 (2)--Seasonally Adjusted Data, 1947-1965 Source: Barger And Klein From Data Developped By Barger In "Outlay And Income In The United States, 1921-1938, " (NBER, 1942).
This NBER data series q08296a appears on the NBER website in Chapter 8 at http://www.nber.org/databases/macrohistory/contents/chapter08.html.
NBER Indicator: q08296a
Release: NBER Macrohistory Database
National Bureau of Economic Research, Gross National Product In Constant Dollars for United States [Q0896AUSQ240SNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q0896AUSQ240SNBR/, October 8, 2015.