United States. Bureau of Economic Analysis. "Gross Domestic Product: First Quarter 2011 (Advance Estimate) : Full Release, BEA 11-19," Bureau of Economic Analysis (BEA) News Releases (April 28, 2011). https://fraser.stlouisfed.org/title/6148/item/604078/content/pdf/bea_newsreleases_20110428, accessed on March 21, 2025.