db/conf/gis/WareJ97.html J. Mark Ware Christopher B. Jones A Data Model for Representing Geological Surfaces. 20-23 GIS1997/P020.pdf 1997 conf/gis/97 ACM-GIS http://doi.acm.org/10.1145/267825.267833 db/conf/gis/gis97.html#WareJ97