United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "March 1978," Business Conditions Digest (March 1978) : 43-45. https://fraser.stlouisfed.org/title/43/item/7379/toc/177261 , accessed on May 1, 2024.
United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "March 1978," Business Conditions Digest (March 1978) : 43-45. https://fraser.stlouisfed.org/title/43/item/7379/toc/177261 , accessed on May 1, 2024.