Daniel Hazel Paul A. Strooper Owen Traynor Possum: An Animator for the SUM Specification Language. 42-51 1997 conf/apsec/1997 APSEC http://csdl.computer.org/comp/proceedings/apsec/1997/8271/00/82710042abs.htm db/conf/apsec/apsec1997.html#HazelST97