United States. Department of Commerce. "U.S. International Trade in Goods and Services, August 2011, BEA 11-51, CB 11-171, FT-900 (11-08),"
United States Department of Commerce News
(October 13, 2011).
https://fraser.stlouisfed.org/title/6148/item/604111, accessed on June 1, 2026.