United States. Bureau of Economic Analysis. "Gross Domestic Product by County, 2020 : Highlights: Gross Domestic Product by County, 2020, BEA 21-63," Bureau of Economic Analysis (BEA) News Releases (December 8, 2021). https://fraser.stlouisfed.org/title/6148/item/610168/content/pdf/bea_newsreleases_20211208_highlights, accessed on March 15, 2025.