Federal Reserve Bank of Chicago. "April 1968," Business Conditions (Federal Reserve Bank of Chicago) (April 1968). https://fraser.stlouisfed.org/title/5562/item/540262, accessed on May 2, 2024.
Federal Reserve Bank of Chicago. "April 1968," Business Conditions (Federal Reserve Bank of Chicago) (April 1968). https://fraser.stlouisfed.org/title/5562/item/540262, accessed on May 2, 2024.