United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "May 1981," Business Conditions Digest (May 1981) : 1-1. https://fraser.stlouisfed.org/title/43/item/7417/toc/358976 , accessed on March 28, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "May 1981," Business Conditions Digest (May 1981) : 1-1. https://fraser.stlouisfed.org/title/43/item/7417/toc/358976 , accessed on March 28, 2024.