@article{polka:fmsd:97,
author={N. Halbwachs and Y.E. Proy and P. Roumanoff},
title={Verification of real-time systems using
linear relation analysis},
journal={Formal Methods in System Design},
year={1997},
month={August},
volume={11},
number={2},
pages={157--185},
publisher={Kluwer},