Felix Weigel Biswanath Panda Mirek Riedewald Johannes Gehrke Manuel Calimlim Large-scale collaborative analysis and extraction of web data. 1476-1479 2008 1 PVLDB 2 http://www.vldb.org/pvldb/1/1454205.pdf db/journals/pvldb/pvldb1.html#WeigelPRGC08