United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "December 1971," Business Conditions Digest (December 1971) : 1-1. https://fraser.stlouisfed.org/title/43/item/7561/toc/77151 , accessed on April 24, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "December 1971," Business Conditions Digest (December 1971) : 1-1. https://fraser.stlouisfed.org/title/43/item/7561/toc/77151 , accessed on April 24, 2024.