United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981) : 2-2. https://fraser.stlouisfed.org/title/43/item/7416/toc/419116 , accessed on April 23, 2024.
United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981) : 2-2. https://fraser.stlouisfed.org/title/43/item/7416/toc/419116 , accessed on April 23, 2024.