@INCOLLECTION{PittsAM:hls,
 AUTHOR={M.~J.~C.~Gordon and A.~M.~Pitts},
 TITLE={The {H}{O}{L} Logic and System},
 BOOKTITLE={Towards Verified Systems},
 CHAPTER=3,
 EDITOR={J.~Bowen},
 SERIES={Real-Time Safety Critical Systems},
 VOLUME=2,
 PUBLISHER={Elsevier Science {B.V.}},
 YEAR=1994,
 PAGES={49-70}}