United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "January 1968," Business Conditions Digest (January 1968) : 1-1. https://fraser.stlouisfed.org/title/43/item/7247/toc/394245 , accessed on April 19, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "January 1968," Business Conditions Digest (January 1968) : 1-1. https://fraser.stlouisfed.org/title/43/item/7247/toc/394245 , accessed on April 19, 2024.