J. Jardine, and S. Teufel. Proceedings of the 14th Conference of the European Chapter of the Association for Computational Linguistics, page 501--510. Gothenburg, Sweden, Association for Computational Linguistics, (April 2014)
P. Yu, X. Li, and B. Liu. Proceedings of the 13th international World Wide Web conference on Alternate track papers & posters, page 448--449. New York, NY, USA, ACM, (2004)
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.