Patrizio Angelini Pier Francesco Cortese Giuseppe Di Battista Maurizio Patrignani Topological Morphing of Planar Graphs. 145-156 2008 Graph Drawing http://dx.doi.org/10.1007/978-3-642-00219-9_15 conf/gd/2008 db/conf/gd/gd2008.html#AngeliniCBP08