United States. Bureau of the Census. "December 1967," Business Conditions Digest (December 1967). https://fraser.stlouisfed.org/title/43/item/7246, accessed on May 10, 2024.
United States. Bureau of the Census. "December 1967," Business Conditions Digest (December 1967). https://fraser.stlouisfed.org/title/43/item/7246, accessed on May 10, 2024.