United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "June 1978," Business Conditions Digest (June 1978) : 79-81. https://fraser.stlouisfed.org/title/43/item/7382/toc/110244 , accessed on April 30, 2024.
United States. Bureau of the Census. "Diffusion Indexes," in United States. Bureau of the Census. "June 1978," Business Conditions Digest (June 1978) : 79-81. https://fraser.stlouisfed.org/title/43/item/7382/toc/110244 , accessed on April 30, 2024.