@inbook{NBERc4602,
 Crossref = "NBERbarg42-1",
 title = "Agricultural Productivity",
 author = "Harold Barger and Hans H. Landsberg",
 BookTitle = "American Agriculture, 1899-1939: A Study of Output, Employment and Productivity",
 Publisher = "NBER",
 pages = "247-288",
 year = "1942",
 URL = "http://www.nber.org/chapters/c4602",
}
@book{NBERbarg42-1,
 title = "American Agriculture, 1899-1939: A Study of Output, Employment and Productivity",
 author = "Harold Barger and Hans H. Landsberg",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1942",
 URL = "http://www.nber.org/books/barg42-1",
}