Harry Uitermark Peter van Oosterom Nicolaas J. I. Mars Martien Molenaar Ontology-Based Geographic Data Set Integration. 60-78 http://link.springer.de/link/service/series/0558/bibs/1678/16780060.htm 1999 conf/stdbm/1999 Spatio-Temporal Database Management db/conf/stdbm/stdbm99.html#UitermarkOMM99