United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "December 1968," Business Conditions Digest (December 1968) : 2-2. https://fraser.stlouisfed.org/title/43/item/7525/toc/389757 , accessed on April 24, 2024.
United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "December 1968," Business Conditions Digest (December 1968) : 2-2. https://fraser.stlouisfed.org/title/43/item/7525/toc/389757 , accessed on April 24, 2024.