United States. Bureau of Economic Analysis. "Gross Domestic Product: Second Quarter 2018 (Second Estimate) | Corporate Profits: Second Quarter 2018 (Preliminary Estimate) : Technical Note, BEA 18-43," Bureau of Economic Analysis (BEA) News Releases (August 29, 2018). https://fraser.stlouisfed.org/title/6148/item/602651/content/pdf/bea_newsreleases_20180829_technical-note, accessed on March 13, 2025.