Kriengkrai Porkaew Iosif Lazaridis Sharad Mehrotra Querying Mobile Objects in Spatio-Temporal Databases. 59-78 2001 conf/ssd/2001 SSTD http://link.springer.de/link/service/series/0558/bibs/2121/21210059.htm db/conf/ssd/sstd2001.html#PorkaewLM01