@inbook{NBERc1578,
 Crossref = "NBERbrad66-1",
 title = "Productivity and Technological Change in the Railroad Sector, 1840-1910 ",
 author = "Albert Fishlow",
 BookTitle = "Output, Employment, and Productivity in the United States after 1800",
 Publisher = "NBER",
 pages = "583-646",
 year = "1966",
 URL = "http://www.nber.org/chapters/c1578",
}
@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",
}