What is ERP? - Helmut Klaus; Michael Rosemann; Guy G. Gable (Inf. Syst. Frontiers, 2000)

Contemplating Open Source Enterprise Systems. - Alexander Dreiling; Helmut Klaus; Michael Rosemann; Boris Wyssusek (WISE, 2004)

On the Foundation of the Ontological Foundation of Conceptual Modeling Grammars: The Construction of the Bunge-Wand-Weber Ontology. - Boris Wyssusek; Helmut Klaus (CAiSE Workshops (2), 2005)

Open Source Enterprise Systems: Towards a Viable Alternative. - Alexander Dreiling; Helmut Klaus; Michael Rosemann; Boris Wyssusek (HICSS, 2005)