DELTA's Virtual Physics Laboratory: A Comprehensive Learning Platform on Physics & Astronomy. - Sepideh Chakaveh; Udo Zlender; Detlef Skaley; Konstantinos Fostiropoulos; Dieter Breitschwerdt (IEEE Visualization, 1999)

Staging the Space of Mixed Reality - Reconsidering the Concept of a Multi User Environment. - Wolfgang Strauss; Monika Fleischmann; Mette Thomsen; Jasminko Novak; Udo Zlender; Thomas Kulessa; Frank Pragasky (VRML, 1999)