Jörg Siebeck Serge S. Shumilov Armin B. Cremers Martin Breunig Andreas Thomsen Selected Spatio-Temporal Data Types and Operations for a 3D/4D Geological Information System. 111-114 2004 conf/ssdbm/2004 SSDBM http://doi.ieeecomputersociety.org/10.1109/SSDBM.2004.62 db/conf/ssdbm/ssdbm2004.html#SiebeckSCBT04