@inbook{NBERc5341,
 Crossref = "NBERmitc21-1",
 title = "Introduction to "Income in the United States: Its Amount and Distribution, 1909-1919, Volume 1: Summary"",
 author = "Wesley Clair Mitchell and Wilford Isbell King and Frederick R. Macaulay",
 BookTitle = "Income in the United States: Its Amount and Distribution, 1909-1919, Volume 1: Summary",
 Publisher = "NBER",
 pages = "1-11",
 year = "1921",
 URL = "http://www.nber.org/chapters/c5341",
}
@book{NBERmitc21-1,
 title = "Income in the United States: Its Amount and Distribution, 1909-1919, Volume 1: Summary",
 author = "Wesley C. Mitchell and Willford I. King and Frederick R. Macaulay and Oswald W. Knauth",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1921",
 URL = "http://www.nber.org/books/mitc21-1",
}