United States. Bureau of Economic Analysis. "Gross Domestic Product: First Quarter 2008 (Advance) : Full Release, BEA 08-18," Bureau of Economic Analysis (BEA) News Releases (April 30, 2008). https://fraser.stlouisfed.org/title/6148/item/600451/content/pdf/bea_newsreleases_20080430, accessed on March 26, 2025.