United States. Bureau of the Census. "Composite Indexes," in United States. Bureau of the Census. "July 1981," Business Conditions Digest (July 1981) : 66-66. https://fraser.stlouisfed.org/title/43/item/7419/toc/226065 , accessed on April 26, 2024.
United States. Bureau of the Census. "Composite Indexes," in United States. Bureau of the Census. "July 1981," Business Conditions Digest (July 1981) : 66-66. https://fraser.stlouisfed.org/title/43/item/7419/toc/226065 , accessed on April 26, 2024.