United States. Bureau of the Census. "Leading Indicators," in United States. Bureau of the Census. "May 1968," Business Conditions Digest (May 1968) : 62-63. https://fraser.stlouisfed.org/title/43/item/7251/toc/131253 , accessed on May 3, 2024.
United States. Bureau of the Census. "Leading Indicators," in United States. Bureau of the Census. "May 1968," Business Conditions Digest (May 1968) : 62-63. https://fraser.stlouisfed.org/title/43/item/7251/toc/131253 , accessed on May 3, 2024.