David Eppstein Marc J. van Kreveld Elena Mumford Bettina Speckmann Edges and Switches, Tunnels and Bridges. 77-88 2007 conf/wads/2007 WADS http://dx.doi.org/10.1007/978-3-540-73951-7_8 db/conf/wads/wads2007.html#EppsteinKMS07