United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "June 1968," Business Conditions Digest (June 1968) : 3-4. https://fraser.stlouisfed.org/title/43/item/7252/toc/428853 , accessed on May 12, 2024.
United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "June 1968," Business Conditions Digest (June 1968) : 3-4. https://fraser.stlouisfed.org/title/43/item/7252/toc/428853 , accessed on May 12, 2024.