@techreport{NBERw13153,
 title = "Pioneers, Submariners, or Thicket-builders:  Which Firms Use Continuations in Patenting? ",
 author = "Deepak Hegde and David C. Mowery and Stuart Graham",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "13153",
 year = "2007",
 month = "June",
 URL = "http://www.nber.org/papers/w13153",
}