@inbook{NBERc2382,
 Crossref = "NBERuniv60-2",
 title = "Differential Fertility in European Countries ",
 author = "Gwendolyn Z. Johnson and Ronald Freedman",
 BookTitle = "Demographic and Economic Change in Developed Countries",
 Publisher = "Columbia University Press",
 pages = "36-76",
 year = "1960",
 URL = "http://www.nber.org/chapters/c2382",
}
@book{NBERuniv60-2,
 title = "Demographic and Economic Change in Developed Countries",
 author = "George B. Roberts, Chairman, Universities-National Bureau Committee for Economic Research",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "Columbia University Press",
 year = "1960",
 URL = "http://www.nber.org/books/univ60-2",
}