United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "June 1968," Business Conditions Digest (June 1968) : 2-2. https://fraser.stlouisfed.org/title/43/item/7252/toc/428852 , accessed on April 26, 2024.
United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "June 1968," Business Conditions Digest (June 1968) : 2-2. https://fraser.stlouisfed.org/title/43/item/7252/toc/428852 , accessed on April 26, 2024.