Farida Semmak Christophe Gnaho Régine Laleau Extended Kaos to Support Variability for Goal Oriented Requirements Reuse. 22-33 2008 MoDISE-EUS http://ceur-ws.org/Vol-341/paper3.pdf conf/caise/2008me db/conf/caise/modise-eus2008.html#SemmakGL08