Federal Reserve Bank of Chicago. "Machinery and Equipment : Key Industries in the Midwest," in Federal Reserve Bank of Chicago. "Annual Report 1966 : Machinery and Equipment: Key Industries in the Midwest," Annual Report of the Federal Reserve Bank of Chicago (January 20, 1967) : 12-35. https://fraser.stlouisfed.org/title/472/item/529820/toc/517560 , accessed on April 23, 2024.