United States. Bureau of the Census. "Composite Indexes," in United States. Bureau of the Census. "April 1972," Business Conditions Digest (April 1972) : 89-89. https://fraser.stlouisfed.org/title/43/item/7565/toc/54957 , accessed on July 9, 2024.
United States. Bureau of the Census. "Composite Indexes," in United States. Bureau of the Census. "April 1972," Business Conditions Digest (April 1972) : 89-89. https://fraser.stlouisfed.org/title/43/item/7565/toc/54957 , accessed on July 9, 2024.