United States. Bureau of Economic Analysis. "Gross Domestic Product: Fourth Quarter and Annual 2012 (Advance Estimate) : Technical Note, BEA 13-02," Bureau of Economic Analysis (BEA) News Releases (January 30, 2013). https://fraser.stlouisfed.org/title/6148/item/601526/content/pdf/bea_newsreleases_20130130_technical-note, accessed on March 15, 2025.