United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "December 1967," Business Conditions Digest (December 1967) : 3-4. https://fraser.stlouisfed.org/title/43/item/7246/toc/425801 , accessed on April 24, 2024.
United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "December 1967," Business Conditions Digest (December 1967) : 3-4. https://fraser.stlouisfed.org/title/43/item/7246/toc/425801 , accessed on April 24, 2024.