Rafael Fernández-Moctezuma Kristin Tufte Jin Li Inter-Operator Feedback in Data Stream Management Systems via Punctuation. 2009 CIDR http://www-db.cs.wisc.edu/cidr/cidr2009/Paper_20.pdf conf/cidr/2009 db/conf/cidr/cidr2009.html#Fernandez-MoctezumaTL09