United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "March 1976," Business Conditions Digest (March 1976) : 90-90. https://fraser.stlouisfed.org/title/43/item/7355/toc/317532 , accessed on April 19, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "March 1976," Business Conditions Digest (March 1976) : 90-90. https://fraser.stlouisfed.org/title/43/item/7355/toc/317532 , accessed on April 19, 2024.