United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "May 1971," Business Conditions Digest (May 1971) : 46-48. https://fraser.stlouisfed.org/title/43/item/7554/toc/129385 , accessed on April 19, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "May 1971," Business Conditions Digest (May 1971) : 46-48. https://fraser.stlouisfed.org/title/43/item/7554/toc/129385 , accessed on April 19, 2024.