Wolfgang A. Halang Peter Vogrin Matjaz Colnaric A Safety Licensable PES for SIL 4 Applications. 141-150 http://link.springer.de/link/service/series/0558/bibs/1943/19430141.htm 2000 conf/safecomp/2000 SAFECOMP db/conf/safecomp/safecomp2000.html#HalangVC00