Kevin Buchin Maike Buchin Jaroslaw Byrka Martin Nöllenburg Yoshio Okamoto Rodrigo I. Silveira Alexander Wolff Drawing (Complete) Binary Tanglegrams: Hardness, Approximation, Fixed-Parameter Tractability http://arxiv.org/abs/0806.0920 2008 CoRR abs/0806.0920 db/journals/corr/corr0806.html#abs-0806-0920 informal publication