@inbook{NBERc0608,
 Crossref = "NBERuniv62-2",
 title = "The Effects of Unions on Industrial Wage Differentials",
 author = "H. Gregg Lewis",
 BookTitle = "Aspects of Labor Economics",
 Publisher = "Princeton University Press",
 pages = "319-344",
 year = "1962",
 URL = "http://www.nber.org/chapters/c0608",
}
@book{NBERuniv62-2,
 title = "Aspects of Labor Economics",
 author = "Harold M. Groves,, Chairman, Universities-National Bureau Committee for Economic Research",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "Princeton University Press",
 year = "1962",
 URL = "http://www.nber.org/books/univ62-2",
}