United States. Bureau of Economic Analysis. "Outdoor Recreation Satellite Account: Updated Statistics for 2012-2016 : Full Release, BEA 18-48," Bureau of Economic Analysis (BEA) News Releases (September 20, 2018). https://fraser.stlouisfed.org/title/6148/item/602656/content/pdf/bea_newsreleases_20180920, accessed on March 21, 2025.