D. Deng, W. Zhang, and S. Lu. Proceedings of the 2013 ACM SIGPLAN International Conference on Object Oriented Programming Systems Languages & Applications, page 785--802. ACM, (2013)
C. Wang, X. Xie, L. Wang, Y. Lu, and W. Ma. Proceedings of the 2005 workshop on Geographic information retrieval, page 17--24. New York, NY, USA, ACM, (2005)