Anna Accornero Massimo Ancona Sonia Varini All Separating Triangles in a Plane Graph Can Be Optimally "Broken" in Polynomial Time. 278-290 http://link.springer.de/link/service/series/0558/bibs/1665/16650278.htm 1999 conf/wg/1999 WG db/conf/wg/wg99.html#AccorneroAV99