United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "September 1981," Business Conditions Digest (September 1981) : 1-1. https://fraser.stlouisfed.org/title/43/item/7421/toc/413836 , accessed on July 15, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "September 1981," Business Conditions Digest (September 1981) : 1-1. https://fraser.stlouisfed.org/title/43/item/7421/toc/413836 , accessed on July 15, 2024.