United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981) : 1-1. https://fraser.stlouisfed.org/title/43/item/7416/toc/419115 , accessed on May 7, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981) : 1-1. https://fraser.stlouisfed.org/title/43/item/7416/toc/419115 , accessed on May 7, 2024.