@techreport{NBERw13498,
 title = "Heterogeneous Impact of the "Seguro Popular" Program on the Utilization of Obstetrical Services in Mexico, 2001-2006:  A Multinomial Probit Model with a Discrete Endogenous Variable",
 author = "Sandra G. Sosa-Rubi and Omar Galarraga and Jeffrey E. Harris",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "13498",
 year = "2007",
 month = "October",
 URL = "http://www.nber.org/papers/w13498",
}