Aris Pagourtzis Paolo Penna Konrad Schlude Kathleen Steinhöfel David Scot Taylor Peter Widmayer Server Placements, Roman Domination and other Dominating Set Variants. 280-291 2002 conf/ifipTCS/2002 IFIP TCS db/conf/ifipTCS/ifipTCS2002.html#PagourtzisPSSTW02