United States. Department of Commerce. "U.S. International Trade in Goods and Services, February 2011, BEA 11-15, CB 11-66, FT-900 (11-02),"
United States Department of Commerce News
(April 12, 2011).
https://fraser.stlouisfed.org/title/6148/item/604074, accessed on June 5, 2026.