United States. Bureau of Economic Analysis. "Gross Domestic Product: Fourth Quarter and Annual 2011 (Advance Estimate) : Technical Note, BEA 12-02," Bureau of Economic Analysis (BEA) News Releases (January 27, 2012). https://fraser.stlouisfed.org/title/6148/item/601316/content/pdf/bea_newsreleases_20120127_technical-note, accessed on March 17, 2025.