United States. Bureau of the Census. "Analytical Ratios," in United States. Bureau of the Census. "April 1969," Business Conditions Digest (April 1969) : 63-64. https://fraser.stlouisfed.org/title/43/item/7529/toc/216903 , accessed on May 5, 2024.
United States. Bureau of the Census. "Analytical Ratios," in United States. Bureau of the Census. "April 1969," Business Conditions Digest (April 1969) : 63-64. https://fraser.stlouisfed.org/title/43/item/7529/toc/216903 , accessed on May 5, 2024.