United States. President and Council of Economic Advisers (U.S.). "United States Merchandise Exports and Imports, by Economic Category," in United States. President and Council of Economic Advisers (U.S.). "1961," Economic Report of the President (1961) : 225-225. https://fraser.stlouisfed.org/title/45/item/8132/toc/400481 , accessed on March 29, 2024.