United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "April 1967," Business Conditions Digest (April 1967) : 1-1. https://fraser.stlouisfed.org/title/43/item/7238/toc/360824 , accessed on April 18, 2024.
United States. Bureau of the Census. "Cover Page," in United States. Bureau of the Census. "April 1967," Business Conditions Digest (April 1967) : 1-1. https://fraser.stlouisfed.org/title/43/item/7238/toc/360824 , accessed on April 18, 2024.