United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "September 1968," Business Conditions Digest (September 1968) : 2-2. https://fraser.stlouisfed.org/title/43/item/7255/toc/137856 , accessed on April 18, 2024.
United States. Bureau of the Census. "Title Page," in United States. Bureau of the Census. "September 1968," Business Conditions Digest (September 1968) : 2-2. https://fraser.stlouisfed.org/title/43/item/7255/toc/137856 , accessed on April 18, 2024.