1. 1. S. Arulampalam, S. Maskell, N. Gordon, and T. Clapp. A tutorial on particle filters for on-line nonlinear/non-gaussian bayesian tracking. IEEE Transactions on Signal Processing, 2001.
   2. L. Backstrom, J. Kleinberg, R. Kumar, and J. Novak. Spatial variation in search engine queries. In Proc. WWW2008, 2008.
   3. T. Bleier and F. Freund. Earthquake warning system. Spectrum, IEEE, 2005.
   4. K. Borau, C. Ullrich, J. Feng, and R. Shen. Microblogging for language learning: Using twitter to train communicative and cultural competence. In Proc. ICWL 2009, pages 78–87, 2009.
   5. d. boyd, S. Golder, and G. Lotan. Tweet, tweet, retweet: Conversational aspects of retweeting on twitter. In Proc. HICSS-43, 2010.
   6. M. Ebner and M. Schiefner. In microblogging.more than fun? In Proc. IADIS Mobile Learning Conference, 2008.
   7. D. Fox, J. Hightower, L. Liao, D. Schulz, and G. Borriello. Bayesian filters for location estimation. IEEE Pervasive Computing, 2003.
   8. G. Grosseck and C. Holotescu. Analysis indicators for communities on microblogging platforms. In Proc. eLSE Conference, 2009.
   9. J. Hightower and G. Borriello. Location systems for ubiquitous computing. IEEE Computer, 34(8):57–66, August 2001.
   10. J. Hightower and G. Borriello. Particle filters for location estimation in ubiquitous computing: A case study. In Proc. UbiComp04, 2004.
   11. B. Huberman and D. R. F. Wu. Social networks that matter: Twitter under the microscope. First Monday, 14, 2009.
   12. B. Jansen, M. Zhang, K. Sobel, and A. Chowdury. Twitter power:tweets as electronic word of mouth. Journal of the American Society for Information Science and Technology, 2009.
   13. A. Java, X. Song, T. Finin, and B. Tseng. Why we twitter: Understanding microblogging usage and communities. In Proc. Joint 9th WEBKDD and 1st SNAKDD Workshop 2007, 2007
   14. T. Joachims. Text categorization with support vector machines. In Proc. ECML’98, pages 137–142, 1998.
   15. J. Leskovec, L. Adamic, and B. Huberman. The dynamics of viral marketing. In Proc. ACM Conference on Electronic Commerce, 2006.
   16. Q. Mei, C. Liu, H. Su, and C. Zhai. A probabilistic approach to spatiotemporal theme pattern mining on weblogs. In Proc. WWW’06, 2006.
   17. Y. Matsuo and H. Yamamoto. Community gravity: measuring bidirectional effects by trust and rating on online social networks. In Proc. WWW2009, 2009.
   18. S. Milstein, A. Chowdhury, G. Hochmuth, B. Lorica, and R. Magoulas. Twitter and the micromessaging revolution: Communication,connections, and immediacy.140 characters at a time. O’Reilly Media, 2008.
   19. M. Naaman, J. Boase, and C. Lai. Is it really about me? Message content in social awareness streams. In Proc. CSCW’09, 2009.
   20. A. Passant, T. Hastrup, U. Bojars, and J. Breslin. Microblogging: A semantic and distributed approach. In Proc. SFSW2008, 2008.
   21. Y. Raimond and S. Abdallah. The event ontology, 2007. http://motools.sf.net/event/event.html.
   22. T. Rattenbury, N. Good, and M. Naaman. Towards automatic extraction of event and place semantics from flickr tags. In Proc. SIGIR 2007, 2007.
   23. E. Scordilis, C. Papazachos, G. Karakaisis, and V. Karakostas. Accelerating sesmic crustal deformation before strong mainshocks in adriatic and its importance for earthquake prediction. Journal of Seismology, 8, 2004.
   24. P. Serdyukov, V. Murdock, and R. van Zwol. Placing flickr photos on a map. In Proc. SIGIR 2009, 2009.
   25. M. Weiser. The computer for the twenty-first century. Scientific American, 268(3):94–104, 1991.