Federal Reserve Bank of Chicago. "May 1968," Business Conditions (Federal Reserve Bank of Chicago) (May 1968). https://fraser.stlouisfed.org/title/5562/item/540263, accessed on March 29, 2024.
Federal Reserve Bank of Chicago. "May 1968," Business Conditions (Federal Reserve Bank of Chicago) (May 1968). https://fraser.stlouisfed.org/title/5562/item/540263, accessed on March 29, 2024.