title: a robust , optimization-based approach for approximate answering of aggregate queries 2001. authors: vivek r. narasayya , gautam das , surajit chaudhuri. venue: sigmod conference. year: nan
title: answering queries with aggregation using views very large data bases. authors: divesh srivastava , shaul dar , h. v. jagadish , alon y. levy. venue: nan. year: 1996.0