United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "July 1975," Business Conditions Digest (July 1975) : 56-57. https://fraser.stlouisfed.org/title/43/item/7347/toc/239363 , accessed on June 27, 2024.
United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "July 1975," Business Conditions Digest (July 1975) : 56-57. https://fraser.stlouisfed.org/title/43/item/7347/toc/239363 , accessed on June 27, 2024.