United States. Bureau of the Census. "Method of Presentation," in United States. Bureau of the Census. "May 1981," Business Conditions Digest (May 1981) : 7-11. https://fraser.stlouisfed.org/title/43/item/7417/toc/358981 , accessed on July 15, 2024.
United States. Bureau of the Census. "Method of Presentation," in United States. Bureau of the Census. "May 1981," Business Conditions Digest (May 1981) : 7-11. https://fraser.stlouisfed.org/title/43/item/7417/toc/358981 , accessed on July 15, 2024.