United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "June 1971," Business Conditions Digest (June 1971) : 85-85. https://fraser.stlouisfed.org/title/43/item/7555/toc/237503 , accessed on May 9, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "June 1971," Business Conditions Digest (June 1971) : 85-85. https://fraser.stlouisfed.org/title/43/item/7555/toc/237503 , accessed on May 9, 2024.