Current Time - Ross, Kenneth A.; Jensen, Christian S.; Snodgrass, Richard; Dyreson, Curtis E.; Skiadopoulos, Spiros; Sirangelo, Cristina; Larsgaard, Mary Lynette; Grahne, Gösta; Kifer, Daniel; Jacobsen, Hans-Arno; Hinterberger, Hans; Deutsch, Alin; et al. (Encyclopedia of Database Systems, 2009)