2012 Official Countdown. Are you Ready For December 2012? Do You Know What Will Happen?
http://MayanCountdown2012.com
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C. Rueda, и M. Gertz. GIS '07: Proceedings of the 15th annual ACM international symposium on Advances in geographic information systems, стр. 1--8. New York, NY, USA, ACM, (2007)