Carla Binucci Walter Didimo Francesco Giordano Maximum Upward Planar Subgraphs of Embedded Planar Digraphs. 195-206 2007 conf/gd/2007 Graph Drawing http://dx.doi.org/10.1007/978-3-540-77537-9_20 db/conf/gd/gd2007.html#BinucciDG07