United States. Bureau of the Census. "Table of Contents," in United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981) : 3-4. https://fraser.stlouisfed.org/title/43/item/7416/toc/419117 , accessed on July 15, 2024.
United States. Bureau of the Census. "Table of Contents," in United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981) : 3-4. https://fraser.stlouisfed.org/title/43/item/7416/toc/419117 , accessed on July 15, 2024.