Catriel Beeri, Shamim A. Naqvi, Raghu Ramakrishnan, Oded Shmueli, Shalom Tsur. Sets and Negation in a Logic Database Language (LDL1). In Proceedings of the Sixth ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, March 23-25, 1987, San Diego, California. pages 21-37, ACM, 1987. [doi]
Abstract is missing.