United States. Bureau of the Census. "Gross National Product," in United States. Bureau of the Census. "May 1971," Business Conditions Digest (May 1971) : 15-15. https://fraser.stlouisfed.org/title/43/item/7554/toc/129368 , accessed on May 8, 2024.
United States. Bureau of the Census. "Gross National Product," in United States. Bureau of the Census. "May 1971," Business Conditions Digest (May 1971) : 15-15. https://fraser.stlouisfed.org/title/43/item/7554/toc/129368 , accessed on May 8, 2024.