Marc Benkert Joachim Gudmundsson Florian Hübner Thomas Wolle Reporting flock patterns. 111-125 2008 41 Comput. Geom. 3 http://dx.doi.org/10.1016/j.comgeo.2007.10.003 db/journals/comgeo/comgeo41.html#BenkertGHW08a