United States. Bureau of Economic Analysis. "Gross Domestic Product: First Quarter 2018 (Second Estimate) | Corporate Profits: First Quarter 2018 (Preliminary Estimate) : Technical Note, BEA 18-24,"
Bureau of Economic Analysis (BEA) News Releases
(May 30, 2018).
https://fraser.stlouisfed.org/title/6148/item/602632/content/pdf/bea_newsreleases_20180530_technical-note, accessed on June 22, 2025.