United States. Bureau of the Census. "Foreign Trade (chart)," in United States. Bureau of the Census. "May 1972," Business Conditions Digest (May 1972) : 54-54. https://fraser.stlouisfed.org/title/43/item/7566/toc/88813 , accessed on June 24, 2024.
United States. Bureau of the Census. "Foreign Trade (chart)," in United States. Bureau of the Census. "May 1972," Business Conditions Digest (May 1972) : 54-54. https://fraser.stlouisfed.org/title/43/item/7566/toc/88813 , accessed on June 24, 2024.