@techreport{NBERt0340,
 title = "The Identification and Economic Content of Ordered Choice Models with Stochastic Thresholds",
 author = "Flavio Cunha and James J. Heckman and Salvador Navarro",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Technical Working Paper Series",
 number = "340",
 year = "2007",
 month = "July",
 URL = "http://www.nber.org/papers/t0340",
}