United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "April 1970," Business Conditions Digest (April 1970) : 85-85. https://fraser.stlouisfed.org/title/43/item/7541/toc/179591 , accessed on April 25, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "April 1970," Business Conditions Digest (April 1970) : 85-85. https://fraser.stlouisfed.org/title/43/item/7541/toc/179591 , accessed on April 25, 2024.