United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "May 1974," Business Conditions Digest (May 1974) : 52-53. https://fraser.stlouisfed.org/title/43/item/7333/toc/382274 , accessed on April 18, 2024.
United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "May 1974," Business Conditions Digest (May 1974) : 52-53. https://fraser.stlouisfed.org/title/43/item/7333/toc/382274 , accessed on April 18, 2024.