Jennifer L. Leopold Allen L. Ambler Meg Heimovics Tyler Palmer A Visual Query System for the Specification and Scientific Analysis of Continual Queries. 203-211 2001 conf/vl/2001 HCC http://csdl.computer.org/comp/proceedings/hcc/2001/0474/00/04740203abs.htm db/conf/vl/hcc2001.html#LeopoldAHP01