United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981). https://fraser.stlouisfed.org/title/43/item/7416, accessed on July 15, 2024.
United States. Bureau of the Census. "April 1981," Business Conditions Digest (April 1981). https://fraser.stlouisfed.org/title/43/item/7416, accessed on July 15, 2024.