@inbook{Hsu_1995,
title={Valid-Time Selection and Projection},
ISBN={9781461522898},
url={http://dx.doi.org/10.1007/978-1-4615-2289-8_13},
DOI={10.1007/978-1-4615-2289-8_13},
booktitle={The TSQL2 Temporal Query Language},
publisher={Springer US},
author={Hsu,
Suchen and Jensen,
Christian S. and Snodgrass,
Richard T.},
year={1995},
pages={251–298} }