@inbook{NBERc1577,
 Crossref = "NBERbrad66-1",
 title = "Productivity Growth in Grain Production in the United States, 1840-60 and 1900-10",
 author = "William N. Parker and Judith L. V. Klein",
 BookTitle = "Output, Employment, and Productivity in the United States after 1800",
 Publisher = "NBER",
 pages = "523-582",
 year = "1966",
 URL = "http://www.nber.org/chapters/c1577",
}
@book{NBERbrad66-1,
 title = "Output, Employment, and Productivity in the United States after 1800",
 author = "Dorothy S. Brady",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1966",
 URL = "http://www.nber.org/books/brad66-1",
}