United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "December 1967," Business Conditions Digest (December 1967) : 1-1. https://fraser.stlouisfed.org/title/43/item/7246/toc/425799 , accessed on April 25, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "December 1967," Business Conditions Digest (December 1967) : 1-1. https://fraser.stlouisfed.org/title/43/item/7246/toc/425799 , accessed on April 25, 2024.