Paul Grünbacher Rick Rabiser Deepak Dhungana Martin Lehofer Structuring the Product Line Modeling Space: Strategies and Examples. 77-82 2009 VaMoS http://www.vamos-workshop.net/proceedings/VaMoS_2009_Proceedings.pdf conf/vamos/2009 db/conf/vamos/vamos2009.html#GrunbacherRDL09