United States. Bureau of the Census. "Table of Contents," in United States. Bureau of the Census. "April 1970," Business Conditions Digest (April 1970) : 3-4. https://fraser.stlouisfed.org/title/43/item/7541/toc/179537 , accessed on April 24, 2024.
United States. Bureau of the Census. "Table of Contents," in United States. Bureau of the Census. "April 1970," Business Conditions Digest (April 1970) : 3-4. https://fraser.stlouisfed.org/title/43/item/7541/toc/179537 , accessed on April 24, 2024.