PPP: A Integrated CASE Environment. - Jon Atle Gulla; Odd Ivar Lindland; Geir Willumsen (CAiSE, 1991)

Using Explanations to Improve the Validation of Executable Models - Jon Atle Gulla; Geir Willumsen (CAiSE, 1993)

Prototyping in Transformation-Based CASE Environments. - Odd Ivar Lindland; Geir Willumsen; Jon Atle Gulla; Arne Sølvberg (SEKE, 1993)

Executing, viewing and explaining conceptual models. - Jon Atle Gulla; Geir Willumsen; Odd Ivar Lindland; Arne Sølvberg (ICRE, 1994)

Integration of Temporal and Incomplete Aspects at the Knowledge Level. - Inge Nordbø; Geir Willumsen (SCAI, 1995)