United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services: December 2016 : Highlights, Annual: 2016 Trade Gap is $502.3 Billion, BEA 17-06, CB 17-17, FT-900 (16-12),"
Bureau of Economic Analysis (BEA) News Releases
(February 7, 2017).
https://fraser.stlouisfed.org/title/6148/item/602477/content/pdf/bea_newsreleases_20170207_release-highlights-annual, accessed on March 26, 2025.