@inbook{NBERc3275,
 Crossref = "NBERhans70-1",
 title = "Introduction to "Education, Income, and Human Capital"",
 author = "W Lee. Hansen",
 BookTitle = "Education, Income, and Human Capital",
 Publisher = "NBER",
 pages = "1-8",
 year = "1970",
 URL = "http://www.nber.org/chapters/c3275",
}
@book{NBERhans70-1,
 title = "Education, Income, and Human Capital",
 author = "W. Lee Hansen",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1970",
 URL = "http://www.nber.org/books/hans70-1",
}