P. Singer, D. Helic, A. Hotho, and M. Strohmaier. International Conference on World Wide Web, page 1003--1013. Republic and Canton of Geneva, Switzerland, International World Wide Web Conferences Steering Committee, (2015)
A. Asahara, K. Maruyama, A. Sato, and K. Seto. International Conference on Advances in Geographic Information Systems (SIGSPATIAL), page 25--33. New York, NY, USA, ACM, (2011)