title: schemasql - a language for interoperability in relational multi-database systems. authors: fereidoon sadri , laks v. s. lakshmanan , iyer n. subramanian. venue: vldb. year: 1996
title: a system for watermarking relational databases. authors: rakesh agrawal , peter j. haas , jerry kiernan. venue: international conference on management of data. year: 2003