Brian Henderson-Sellers Cesar Gonzalez-Perez The Rationale of Powertype Powertype-based Metamodelling to Underpin nderpin Software D Development evelopment Methodologies. 7-16 2005 conf/apccm/2005 APCCM http://crpit.com/confpapers/CRPITV43HendersonSellers.pdf db/conf/apccm/apccm2005.html#Henderson-SellersG05