United States. Bureau of the Census. "March 1971," Business Conditions Digest (March 1971). https://fraser.stlouisfed.org/title/43/item/7552, accessed on June 23, 2024.
United States. Bureau of the Census. "March 1971," Business Conditions Digest (March 1971). https://fraser.stlouisfed.org/title/43/item/7552, accessed on June 23, 2024.