Blondel, V. D. et al.: Fast unfolding of communities in large networks, Journal of Statistical Mechanics: Theory and Experiment, Vol. 2008, No. 10, p. P10008 (2008).
Jain, K. et al.: A New Greedy Approach for Facility Location Problems, Proceedings of the Thiry-fourth Annual ACM Symposium on Theory of Computing, pp. 731-740 (2002).