Towards Interoperability: Vertical Integration of Languages with a KBMS. - Wolfgang Benn; Christian Kortenbreer; Xinglin Wu (BTW, 1991)

Berichte von der BTW'91. - Christian Kortenbreer; Vera Goebel (Datenbank Rundbr., 1991)

On Interoperability for KBMS Applications - The Horizontal Integration Task. - Wolfgang Benn; Christian Kortenbreer; Gunter Schlageter; Xinglin Wu (ICDE, 1992)