Jan Bosch Gert Florijn Danny Greefhorst Juha Kuusela J. Henk Obbink Klaus Pohl Variability Issues in Software Product Lines. 13-21 2001 conf/pfe/2001 PFE http://link.springer.de/link/service/series/0558/bibs/2290/22900013.htm db/conf/pfe/pfe2001.html#BoschFGKOP01