Marc Benkert Joachim Gudmundsson Christian Knauer René van Oostrum Alexander Wolff A Polynomial-Time Approximation Algorithm for a Geometric Dispersion Problem. 267-288 2009 19 Int. J. Comput. Geometry Appl. 3 http://dx.doi.org/10.1142/S0218195909002952 db/journals/ijcga/ijcga19.html#BenkertGKOW09