@inbook{NBERc5130,
 Crossref = "NBERfere29-1",
 title = "Migrations According to International Statistics: Intercontinenal Movements",
 author = "Walter F. Willcox",
 BookTitle = "International Migrations, Volume I: Statistics",
 Publisher = "NBER",
 pages = "163-219",
 year = "1929",
 URL = "http://www.nber.org/chapters/c5130",
}
@book{NBERfere29-1,
 title = "International Migrations, Volume I: Statistics",
 author = "Walter F. Willcox",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1929",
 URL = "http://www.nber.org/books/fere29-1",
}