Dirk Jäger Ansgar Schleicher Bernhard Westfechtel AHEAD: A Graph-Based System for Modeling and Managing Development Processes. 325-339 http://link.springer.de/link/service/series/0558/bibs/1779/17790325.htm 1999 conf/agtive/1999 AGTIVE db/conf/agtive/agtive1999.html#JagerSW99