United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "April 1969," Business Conditions Digest (April 1969) : 84-84. https://fraser.stlouisfed.org/title/43/item/7529/toc/216925 , accessed on April 25, 2024.
United States. Bureau of the Census. "Aggregate Series," in United States. Bureau of the Census. "April 1969," Business Conditions Digest (April 1969) : 84-84. https://fraser.stlouisfed.org/title/43/item/7529/toc/216925 , accessed on April 25, 2024.