Mattias Andersson Joachim Gudmundsson Patrick Laube Thomas Wolle Reporting Leaders and Followers among Trajectories of Moving Point Objects. 497-528 2008 12 GeoInformatica 4 http://dx.doi.org/10.1007/s10707-007-0037-9 db/journals/geoinformatica/geoinformatica12.html#AnderssonGLW08