@article\{bdg-mupsepd-08
, author =	"Carla Binucci and Walter Didimo and Francesco Giordano"
, title =	"Maximum Upward Planar subgraphs of Embedded Planar Digraphs"
, journal =	"Computational Geometry: Theory and Applications"
, volume =	41
, number =	"3"
, pages =	"230-246"
, year =	2008
}