Philipp Liegl Rainer Schuster Marco Zapletal Christian Huemer Hannes Werthner Michael Aigner Martin Bernauer Bjoern Klinger Michaela Mayr Ramin Mizani Martin Windisch [vem: xi: ] - A Methodology for Process Based Requirements Engineering. 193-202 2009 RE http://doi.ieeecomputersociety.org/10.1109/RE.2009.18 conf/re/2009 db/conf/re/re2009.html#LieglSZHWABKMMW09