United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services, June 2021 : Historical Comparisons, BEA 21-38, CB 21-121," Bureau of Economic Analysis (BEA) News Releases (August 5, 2021). https://fraser.stlouisfed.org/title/6148/item/604964/content/pdf/bea_newsreleases_20210805_historical, accessed on March 26, 2025.