Federal Reserve Bank of Chicago. "September 1968," Business Conditions (Federal Reserve Bank of Chicago) (September 1968). https://fraser.stlouisfed.org/title/5562/item/540267, accessed on April 23, 2024.
Federal Reserve Bank of Chicago. "September 1968," Business Conditions (Federal Reserve Bank of Chicago) (September 1968). https://fraser.stlouisfed.org/title/5562/item/540267, accessed on April 23, 2024.