Extending the Frontier of Economic Science
    Published Date 
  
  
    Copyright 1928
  
 
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      Copy CitationEdwin F. Gay and Wesley C. Mitchell, Extending the Frontier of Economic Science: Report of the Directors of Research of the National Bureau of Economic Research for the Year 1927 (NBER, 1928), https://www.nber.org/books-and-chapters/extending-frontier-economic-science-report-directors-research-national-bureau-economic-research-year/extending-frontier-economic-science.