United States. Bureau of Economic Analysis. "Gross Domestic Product: Fourth Quarter and Annual 2013 (Second Estimate) : Technical Note, BEA 14-06,"
Bureau of Economic Analysis (BEA) News Releases
(February 28, 2014).
https://fraser.stlouisfed.org/title/6148/item/602086/content/pdf/bea_newsreleases_20140228_technical-note, accessed on June 24, 2025.