United States. Bureau of Economic Analysis. "Gross Domestic Product, Third Quarter 2018 (Advance Estimate) : Technical Note, BEA 18-56," Bureau of Economic Analysis (BEA) News Releases (October 25, 2018). https://fraser.stlouisfed.org/title/6148/item/602664/content/pdf/bea_newsreleases_20181025_technical-note, accessed on March 20, 2025.