1. Abiteboul, S., Hull, R., Vianu, V.: Foundations of Databases. Addison-Wesley (1995)
2. Codd, E.: A Relational Model for Large Shared Databanks. Communications of the ACM 13(6), 377–390 (1970)
3. Date, C.J.: SQL and relational theory: how to write accurate SQL code. O’Reilly, Sebastopol (2009)
4. Finkelstein, S.J., Mattos, N., Mumick, I.S., Pirahesh, H.: Expressing recursive queries in SQL. Technical report, ISO (1996)
5. Garcia-Molina, H., Ullman, J.D., Widom, J.: Database systems - the complete book, 2nd edn. Pearson Education (2009)