United States. Bureau of Economic Analysis. "Prototype Gross Domestic Product by County, 2012-2015 : Full Release, BEA 18-67," Bureau of Economic Analysis (BEA) News Releases (December 12, 2018). https://fraser.stlouisfed.org/title/6148/item/602675/content/pdf/bea_newsreleases_20181212, accessed on March 23, 2025.