United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "January 1971," Business Conditions Digest (January 1971) : 1-1. https://fraser.stlouisfed.org/title/43/item/7550/toc/171236 , accessed on April 25, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "January 1971," Business Conditions Digest (January 1971) : 1-1. https://fraser.stlouisfed.org/title/43/item/7550/toc/171236 , accessed on April 25, 2024.