@inproceedings{li2014foursquare,
  title={Region Sampling and Estimation of GeoSocial Data with Dynamic Range Calibration},
  author={Yanhua Li and Moritz Steiner and Jie Bao and Limin Wang and Ting Zhu},
  booktitle={ICDE'14: The 30th International Conference on Data Engineering},
  pages={1--12},
  year={2014}
}