Ahlemann, Frederik: Towards a conceptual reference model for project management information systems, in: International Journal of Project ManagementVolume 27 (2009), No. 1, pp 19-30.doi:10.1016/j.ijproman.2008.01.008 In his article Ahlemann shows the different functional nodes, from a business perspective of PMIS systems, structurally sorted by main user groups and life cycle stages. Furthermore the article maps all the needed data structures in huge but very nice UML diagrams. Ahlemann calls this reference model RefModPM.