United States. Bureau of the Census. "Lagging Indicators," in United States. Bureau of the Census. "June 1968," Business Conditions Digest (June 1968) : 30-31. https://fraser.stlouisfed.org/title/43/item/7252/toc/428862 , accessed on April 19, 2024.
United States. Bureau of the Census. "Lagging Indicators," in United States. Bureau of the Census. "June 1968," Business Conditions Digest (June 1968) : 30-31. https://fraser.stlouisfed.org/title/43/item/7252/toc/428862 , accessed on April 19, 2024.