United States. Bureau of the Census. "Foreign Trade," in United States. Bureau of the Census. "March 1970," Business Conditions Digest (March 1970) : 52-52. https://fraser.stlouisfed.org/title/43/item/7540/toc/227155 , accessed on April 19, 2024.
United States. Bureau of the Census. "Foreign Trade," in United States. Bureau of the Census. "March 1970," Business Conditions Digest (March 1970) : 52-52. https://fraser.stlouisfed.org/title/43/item/7540/toc/227155 , accessed on April 19, 2024.