@InProceedings{BaarBeckertSchmitt2001,
author = {Thomas Baar and Bernhard Beckert and Peter H. Schmitt},
title = {An Extension of {D}ynamic {L}ogic for Modelling
{OCL}'s {$@pre$} Operator},
booktitle = {Fourth Andrei Ershov International
Conference on Perspectives of System Informatics},
venue = {Novosibirsk, Russia},
publisher = {Springer},
series = {LNCS},
volume = {2244},
pages = {47--54},
year = {2001}
}