Quellenverzeichnis

Egenhofer, M.J., Sharma, J. & D.M. Mark (1993): A Critical Comparison of the 4-Intersection and 9-Intersection Models for Spatial Relations: Formal Analysis. In: Eleventh International Symposium on Computer-Assisted Cartography. Minneapolis, Minnesota, USA: American Society for Photogrammetry and Remote Sensing (ASPRS), 316-336.online
GITTA (2005). Einführung in Datenbanksysteme [online]. Available from: [http://www.gitta.info/website/en/html/modules_overview.html] [Accessed 19.3.2009].