1. Non first normal form relations to represent hierarchically organized data;Abiteboul,1984
2. The effect of large main memory on database system;Bitton,1986
3. Repetitive bibliographical information in relational databases;Brooks;Journal of the American Society for Information Science,1988
4. A recursive algebra and query optimization for nested relations;Colby,1989
5. The relational model in information retrieval;Crawford;Journal of the American Society for Information Science,1981