Yong Xia Martin Glinz Extending a Graphic Modeling Language to Support Partial and Evolutionary Specification. 18-27 2004 conf/apsec/2004 APSEC http://doi.ieeecomputersociety.org/10.1109/APSEC.2004.51 db/conf/apsec/apsec2004.html#XiaG04