United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "March 1975," Business Conditions Digest (March 1975) : 50-51. https://fraser.stlouisfed.org/title/43/item/7343/toc/63822 , accessed on April 28, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "March 1975," Business Conditions Digest (March 1975) : 50-51. https://fraser.stlouisfed.org/title/43/item/7343/toc/63822 , accessed on April 28, 2024.