United States. Bureau of the Census. "March 1970," Business Conditions Digest (March 1970). https://fraser.stlouisfed.org/title/43/item/7540, accessed on April 25, 2024.
United States. Bureau of the Census. "March 1970," Business Conditions Digest (March 1970). https://fraser.stlouisfed.org/title/43/item/7540, accessed on April 25, 2024.