United States. Bureau of the Census. "Lagging Indicators," in United States. Bureau of the Census. "May 1968," Business Conditions Digest (May 1968) : 30-31. https://fraser.stlouisfed.org/title/43/item/7251/toc/131242 , accessed on May 7, 2024.
United States. Bureau of the Census. "Lagging Indicators," in United States. Bureau of the Census. "May 1968," Business Conditions Digest (May 1968) : 30-31. https://fraser.stlouisfed.org/title/43/item/7251/toc/131242 , accessed on May 7, 2024.