United States. Bureau of the Census. "Series Finding Guide," in United States. Bureau of the Census. "June 1967," Business Conditions Digest (June 1967) : 87-89. https://fraser.stlouisfed.org/title/43/item/7240/toc/196665 , accessed on May 4, 2024.
United States. Bureau of the Census. "Series Finding Guide," in United States. Bureau of the Census. "June 1967," Business Conditions Digest (June 1967) : 87-89. https://fraser.stlouisfed.org/title/43/item/7240/toc/196665 , accessed on May 4, 2024.