Linnemann, V. et al "Design and Implementation of an Extensible Database Management System Supporting User Defined Data Types and Functions"

[Proceedings] (1988) Proceedings of the 14th VLDB Conference Los Angeles, California 1988  

Languages mentioned Galileo {1983} interactive, strictly-typed data base programming language ISBL {1974} IBM Peterlee experimental relational algebra POSTQUEL {1986} PROBE {1987} Taxis {1980}