Max J. Egenhofer Janice I. Glasgow Oliver Günther John R. Herring Donna Peuquet Progress in computational methods for representing geographical concepts. 775-796 1999 13 International Journal of Geographical Information Science 8 http://dx.doi.org/10.1080/136588199241012 db/journals/gis/gis13.html#EgenhoferGGHP99