Hubert Lehmann, Albrecht Blaser. Query Languages in Data Base Systems. In Karl-Heinz Böhling, Peter Paul Spies, editors, GI - 9. Jahrestagung, Bonn, 1.-5. Oktober 1979, Proceedings. Volume 19 of Informatik-Fachberichte, pages 64-80, Springer, 1979.
Abstract is missing.