@techreport{NBERw12150,
 title = "Abortion and Selection",
 author = "Elizabeth Oltmans Ananat and Jonathan Gruber and Phillip B. Levine and Douglas Staiger",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "12150",
 year = "2006",
 month = "April",
 URL = "http://www.nber.org/papers/w12150",
}