United States. Department of Commerce. "U.S. International Trade in Goods and Services, June 2011, BEA 11-41, CB 11-139, FT-900 (11-06),"
United States Department of Commerce News
(August 11, 2011).
https://fraser.stlouisfed.org/title/6148/item/604101, accessed on June 2, 2026.