United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "May 1967," Business Conditions Digest (May 1967) : 3-4. https://fraser.stlouisfed.org/title/43/item/7239/toc/401934 , accessed on April 19, 2024.
United States. Bureau of the Census. "Contents," in United States. Bureau of the Census. "May 1967," Business Conditions Digest (May 1967) : 3-4. https://fraser.stlouisfed.org/title/43/item/7239/toc/401934 , accessed on April 19, 2024.