S. Maslov, and S. Redner. (2009)cite arxiv:0901.2640
Comment: 3 pages, 1 figure, invited comment for the Journal of Neuroscience.
The arxiv version is microscopically different from the published version.
R. Yan, J. Tang, X. Liu, D. Shan, and X. Li. Proceedings of the 20th ACM international conference on Information and knowledge management, page 1247--1252. New York, NY, USA, ACM, (2011)