United States. Bureau of the Census. "Leading Indicators," in United States. Bureau of the Census. "April 1968," Business Conditions Digest (April 1968) : 14-14. https://fraser.stlouisfed.org/title/43/item/7250/toc/84831 , accessed on May 3, 2024.
United States. Bureau of the Census. "Leading Indicators," in United States. Bureau of the Census. "April 1968," Business Conditions Digest (April 1968) : 14-14. https://fraser.stlouisfed.org/title/43/item/7250/toc/84831 , accessed on May 3, 2024.