U.S. International Economic Accounts: Concepts and Methods: http://www.bea.gov/international/concepts_methods.htm   US direct investment abroad: http://www.bea.gov/international/pdf/usdia_2009r/Introduction.pdf   FDI in the US: http://www.bea.gov/international/pdf/fdius_2012f/Text%20Sections%20-%20FDIUS%202012-Final.pdf