KyoungSoo Park Vivek S. Pai Kang-Won Lee Seraphin B. Calo Securing Web Service by Automatic Robot Detection. 255-260 2006 conf/usenix/2006g USENIX Annual Technical Conference, General Track http://www.usenix.org/events/usenix06/tech/park.html db/conf/usenix/usenix2006g.html#ParkPLC06