United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "July 1973," Business Conditions Digest (July 1973) : 91-91. https://fraser.stlouisfed.org/title/43/item/7323/toc/158519 , accessed on April 25, 2024.
United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "July 1973," Business Conditions Digest (July 1973) : 91-91. https://fraser.stlouisfed.org/title/43/item/7323/toc/158519 , accessed on April 25, 2024.