1. G. Abrantes, R. Carapuca, Explicit representation of data depend on topological relationships and control over data consistency, in: Proceedings of the 5th European Conference and Exhibition on GIS (EGIS/MARI), Paris, France, 1994, pp. 869–877.
2. Formalization of the Whole–Part Relationship in the Unified Modeling Language;Barbier;IEEE Trans. Software Eng.,2003
3. Adapting data models for the design of spatio-temporal databases;Bédard;Comput. Environ. Urban Syst.,1996
4. Visual Modelling of Spatial Databases: towards spatial PVL and UML;Bédard;GEOMATICA,1999
5. A. Belussi, M. Negri, G. Pelagatti, GeoUML: an ISO TC 211 compatible data model for the conceptual design of geographic databases, Internal report N. 2004.21, Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy, 2004.