United States. Bureau of Economic Analysis. "National Income and Product Accounts : Historical Comparison : Gross Domestic Product: Second Quarter 2013 (Advance Estimate) | Comprehensive Revision: 1929 Through First Quarter 2013, BEA 13-34," Bureau of Economic Analysis (BEA) News Releases (July 31, 2013). https://fraser.stlouisfed.org/title/6148/item/601557/content/pdf/bea_newsreleases_20130731_historical-comparisons, accessed on March 19, 2025.