United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "June 1973," Business Conditions Digest (June 1973) : 52-53. https://fraser.stlouisfed.org/title/43/item/7322/toc/166880 , accessed on March 29, 2024.
United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "June 1973," Business Conditions Digest (June 1973) : 52-53. https://fraser.stlouisfed.org/title/43/item/7322/toc/166880 , accessed on March 29, 2024.