United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "May 1969," Business Conditions Digest (May 1969) : 46-48. https://fraser.stlouisfed.org/title/43/item/7530/toc/303365 , accessed on April 24, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "May 1969," Business Conditions Digest (May 1969) : 46-48. https://fraser.stlouisfed.org/title/43/item/7530/toc/303365 , accessed on April 24, 2024.