United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "July 1968," Business Conditions Digest (July 1968) : 3-4. https://fraser.stlouisfed.org/title/43/item/7253/toc/409149 , accessed on April 25, 2024.
United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "July 1968," Business Conditions Digest (July 1968) : 3-4. https://fraser.stlouisfed.org/title/43/item/7253/toc/409149 , accessed on April 25, 2024.