Nieves Atienza Natalia de Castro Carmen Cortés Maria Angeles Garrido Clara I. Grima Gregorio Hernández Alberto Márquez Auxiliadora Moreno-González Martin Nöllenburg José Ramón Portillo Pedro Reyes Jesus Valenzuela Maria Trinidad Villar Alexander Wolff Cover Contact Graphs. 171-182 2007 conf/gd/2007 Graph Drawing http://dx.doi.org/10.1007/978-3-540-77537-9_18 db/conf/gd/gd2007.html#AtienzaCCGGHMMNPRVVW07