http://dx.doi.org/10.1007/3-540-63238-7_23 Edwin M. Knorr Raymond T. Ng David L. Shilvock Finding Boundary Shape Matching Relationships in Spatial Data. 29-46 SSD/1997/P029.pdf 1997 conf/ssd/97 SSD db/conf/ssd/ssd97.html#KnorrNS97