United States. Bureau of the Census. "Foreign Trade," in United States. Bureau of the Census. "May 1970," Business Conditions Digest (May 1970) : 52-52. https://fraser.stlouisfed.org/title/43/item/7542/toc/272008 , accessed on April 18, 2024.
United States. Bureau of the Census. "Foreign Trade," in United States. Bureau of the Census. "May 1970," Business Conditions Digest (May 1970) : 52-52. https://fraser.stlouisfed.org/title/43/item/7542/toc/272008 , accessed on April 18, 2024.