@inbook{NBERc9182,
 Crossref = "NBERaesm72-1",
 title = "Firm Data and Industry Aggregates in the Analysis of Diversification and Integration",
 author = "Michael Gort and Swarnjit Arora and Robert McGuckin",
 BookTitle = "Annals of Economic and Social Measurement, Volume 1, number 1",
 Publisher = "NBER",
 pages = "36-40",
 year = "1972",
 URL = "http://www.nber.org/chapters/c9182",
}
@book{NBERaesm72-1,
 title = "Annals of Economic and Social Measurement, Volume 1, number 1",
 author = "Sanford V. Berg, editor",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1972",
 URL = "http://www.nber.org/books/aesm72-1",
}