United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "April 1971," Business Conditions Digest (April 1971) : 2-2. https://fraser.stlouisfed.org/title/43/item/7553/toc/368642 , accessed on May 4, 2024.
United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "April 1971," Business Conditions Digest (April 1971) : 2-2. https://fraser.stlouisfed.org/title/43/item/7553/toc/368642 , accessed on May 4, 2024.