United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "September 1971," Business Conditions Digest (September 1971) : 1-1. https://fraser.stlouisfed.org/title/43/item/7558/toc/69598 , accessed on March 29, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "September 1971," Business Conditions Digest (September 1971) : 1-1. https://fraser.stlouisfed.org/title/43/item/7558/toc/69598 , accessed on March 29, 2024.