Richard T. Snodgrass Michael H. Böhlen Christian S. Jensen Andreas Steiner Transitioning Temporal Support in TSQL2 to SQL3. 150-194 1997 Temporal Databases, Dagstuhl db/conf/dagstuhl/dagstuhl-tdb97.html#SnodgrassBJS97 http://link.springer.de/link/service/series/0558/bibs/1399/13990150.htm