United States. Bureau of the Census. "Foreign Trade," in United States. Bureau of the Census. "July 1971," Business Conditions Digest (July 1971) : 52-52. https://fraser.stlouisfed.org/title/43/item/7556/toc/149232 , accessed on April 23, 2024.
United States. Bureau of the Census. "Foreign Trade," in United States. Bureau of the Census. "July 1971," Business Conditions Digest (July 1971) : 52-52. https://fraser.stlouisfed.org/title/43/item/7556/toc/149232 , accessed on April 23, 2024.