Jayant Madhavan David Ko Lucja Kot Vignesh Ganapathy Alex Rasmussen Alon Y. Halevy Google's Deep Web crawl. 1241-1252 2008 1 PVLDB 2 http://www.vldb.org/pvldb/1/1454163.pdf db/journals/pvldb/pvldb1.html#MadhavanKKGRH08