United States. Bureau of the Census. "Analytical Measures," in United States. Bureau of the Census. "May 1969," Business Conditions Digest (May 1969) : 14-14. https://fraser.stlouisfed.org/title/43/item/7530/toc/303347 , accessed on April 24, 2024.
United States. Bureau of the Census. "Analytical Measures," in United States. Bureau of the Census. "May 1969," Business Conditions Digest (May 1969) : 14-14. https://fraser.stlouisfed.org/title/43/item/7530/toc/303347 , accessed on April 24, 2024.