United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services, Annual Revision : Highlights: April 2021 Trade Gap is $68.9 Billion, BEA 21-25, CB 21-89," Bureau of Economic Analysis (BEA) News Releases (June 8, 2021). https://fraser.stlouisfed.org/title/6148/item/604264/content/pdf/bea_newsreleases_20210608a_highlights, accessed on March 22, 2025.