@inproceedings{HagueOng2007, title = "Symbolic Backwards Reachability Analysis for Higher-Order Pushdown Systems", author = "M. Hague and C.-H. L. Ong", year = "2007", booktitle = "FoSSaCS", note = "<a href="http://www.comlab.ox.ac.uk/people/matthew.hague/FoSSaCS07-long.pdf">Long Version (pdf)</a>", }